The State of Finnish Coastal Waters in the 1990S

472 The Finnish Environment The Finnish Environment 472 The state of Finnish coastal waters in the 1990s

ENVIRONMENTAL ENVIRONMENTAL PROTECTION PROTECTION

The state of Finnish coastal waters in the 1990s Pirkko Kauppila and Saara Bäck (eds)

The ecological status of coastal waters still is an important environmental issue. Especially the shallow Finnish coastal zone is in many respects sensitive to pollution and eutrophication. The The state long term point-source loading of watercourses, especially by nutrients and harmful substances, as well as the indirect effects of increasing demand for different land use e.g agriculture and of Finnish coastal waters building activities in catchment areas have had deteriorating effects in many ways. in the 1990s This report is the second national effort to compile monitoring information on the changes in water quality in Finnish coastal waters. The report is based on the results of different monitoring programmes, loading statistics and studies concerning the state of Finnish coastal water areas. In this report data and information have been collected using the national data bases in which the monitoring data are stored and maintained. In addition to nutrients and harmful substances, monitoring data of phytoplankton and macrozoobenthos are also evaluated. Moreover, the available data on phytobenthos changes originated from separate research projects were evaluated. The report covers the years from the the early 1980s to 1998/2000.

The report cover the following topics

• loading of nutrients and harmful substances originating from different sources

• assessment of the effects of loading on chemical and biological water quality in coastal areas

• assessment of changes in the state of coastal waters during the 1990s and reasons for those

• phytobenthos and macrozoobenthos changes as a measure of the state of coastal waters

• changes in fish populations and fisheries

ISBN 952-11-0878-9 ISSN 1238-7312

•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• FINNISH ENVIRONMENT INSTITUTE P.O.BOX 140, FIN-00251 HELSINKI FINNISH ENVIRONMENT INSTITUTE The publication is also available in the internet http://www.vyh.fi/palvelut/julkaisu/elektro/fe472/fe472.htm

ISBN 952-11-0878-9 ISSN 1238-7312

Maps: Maanmittauslaitos, permission no 7/MYY/01

Cover photo: Pirkko Kauppila Page-layout: DTPage Oy

Printinghouse: Vammalan Kirjapaino Oy, 2001 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

2 ○○○○○○○○○○ The Finnish Environment 472 Preface

The status of Finnish coastal waters is an important environmental issue. Espe- cially the shallow coastal zone is in many respects sensitive to pollution and eutrophication. The long term loading of nutrients and harmful substances of the catchment areas have had deteriorating effects in many ways. Finally the loading reaches coastal waters and affects the coastal zone. Water protection measures based on sound assessment information are urgently needed. Improve- ment of the ecological status of coastal waters and conservation of coastal areas are also required by the EU Water Policy Directive and the Habitats directive as well as by many international agreements, such as the HELCOM convention, the Ramsar convention and the Convention on biodiversity. Numerous scientific articles and areal reports deal with Finnish coastal waters. However, only some reports provide the reader with general view of coastal water quality such as HELCOM periodic assessments of the state of the marine environment of the Baltic Sea. This report is the second national effort to compile information on the changes in water quality in Finnish coastal waters. In addition to nutrients and harmful substances, monitoring data of phytoplankton and macrozoobenthos are also evaluated. Moreover, the available data on phytobenthos changes originated from separate research projects and it was evaluated. The report covers the years from the the early 1980s to the late 1990s. In addition to international, national and administrative requirements, the report also focus on providing information on coastal water state for the public. The assessment is mainly based on the coastal monitoring data produced by the Finnish Environment Institute (FEI). The physical and chemical monitoring data in open sea areas originated from the Finnish Institute of Marine Re- search (FIRM). The section on fish catches was delivered by the Finnish Game and Fisheries Research Institute. Numerous scientific arcticles and reports were evaluated to assess the changes in phytobenthos because monitoring data for phytobenthos was not available. Additionally, local pollution control studies were utilized in order to obtain additional information on zoobenthos and harmful substances in polluted water areas. The editors are grateful to the group of the collegues both in FEI and FIRM for their contributions to the report. We would like to express our warmest thanks to Sirkka Vuoristo who finialised the figures of this report, Petri Porvari for his participation to GIS-work, Antti-Räike and Anna-Maija Beloff who participated in compiling the data, Kati Manni, Petri Ekholm, Jussi Vuorenmaa and Jouni Lehtoranta for their contributions to the text for “information boxes”. The Eng- lish language was revised by Michael Bailey. We thank Doc. Matti Perttilä in FIRM and Teija Kirkkala in the Southwest Finland Environment Centre for their

valuable comments on the manuscript. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 3 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

4 ○○○○○○○○○○ The Finnish Environment 472 Contents

Preface ...... 3 1 Introduction ...... 7 1.1 Content and purpose of this report ...... 7 1.2 Coastal water monitoring...... 8 1.3 International framework ...... 12

2 Main characteristics of Finnish coastal waters...... 13 3 Loading of pollutants ...... 15 3.1 Nutrient loading and its source apportionment ...... 15 3.2 Trends in the nutrient loads in 1985–1998 ...... 22 3.3 Loading of organic matter and its trends in 1985–1997...... 27 3.4 Loading of harmful substances ...... 27

4 Hydrography and oxygen conditions...... 30 4.1 Salinity ...... 30 4.2 Oxygen ...... 35

5 Nutrients ...... 37 5.1 Spatial distribution of phosphorus and nitrogen ...... 37 5.1.1 Winter ...... 37 5.1.2 Late summer ...... 45 5.1.3 Inorganic N:P ratio ...... 49 5.2 Trends since the late 1980s ...... 51 5.2.1 The Gulf of Finland ...... 51 5.2.2 The Archipelago Sea ...... 51 5.2.3 The Bothnian Sea and the Bothnian Bay ...... 58 6 Changes in phytoplankton ...... 61 6.1 Areal distribution of phytoplankton chlorophyll a ...... 61 6.2 Seasonal variations of phytoplankton ...... 64 6.3 Long term changes in phytoplankton ...... 66 6.4 Nuisance algal blooms ...... 68

7 Changes in phytobenthos ...... 71 7.1 Species composition of macroalgae ...... 71 7.2 Fucus vesiculosus recovery ...... 72 7.3 Soft bottom vegetation ...... 73 7.4 Mass occurrence of macroalgae ...... 74 7.5 Littoral fauna ...... 77 7.6 Decline of Mytilus edulis ...... 77 7.7 Newcomers ...... 78

8 Changes in zoobenthic communities ...... 79 8.1 The Bothnian Bay ...... 79 8.2 The Bothnian Sea ...... 80

8.3 The Turku area in the Archipelago Sea ...... 82 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 5 8.4 The Gulf of Finland ...... 83 8.5 Zoobenthos trends in a reference area in Tvärminne ...... 85 8.6 General zoobenthos trends in the Finnish coastal waters ...... 86

9 Fish stocks and fisheries ...... 89 9.1 Migratory species ...... 89 9.2 Limnic species ...... 89 9.3 Marine species ...... 91 9.4 Direct harmful effects on fishery ...... 92

10 Harmful substances ...... 94 10.1 Heavy metals ...... 94 10.1.1 Sediment...... 94 10.1.2 Zoobenthos ...... 95 10.1.3 Hg in fish...... 96 10.2 Organic pollutants ...... 99 10.2.1 Sediment...... 99 10.2.2 Zoobenthos ...... 99 10.2.3 Fish ...... 100 10.3 Oil and other contaminants from the petrochemical industry ...... 104 10.3.1 Sediments ...... 104 10.3.2 Fish ...... 104

11 Classification of coastal water quality...... 105 Summary in English and in Finnish ...... 109 References...... 122

Documentation pages ...... 132 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

6 ○○○○○○○○○○ The Finnish Environment 472

Introduction

○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 1

1.1 Context and purpose This report is the second national effort to compile monitoring informa- of this assessment report tion on the changes in water quality in Finnish coastal waters. In addition to The ecological status of coastal waters nutrients and harmful substances, has been and still is in most European monitoring data of phytoplankton and countries an important environmental macrozoobenthos are also evaluated. issue. The long term point-source load- Moreover, the available data on phy- ing of watercourses, especially by nu- tobenthos changes originated from trients, as well as the indirect effects of separate research projects and it was increasing demand for different land evaluated. The report covers the years use e.g agriculture and building activ- from the the early 1980s to 1998/2000. ities in catchment areas and the con- The objectives of the report are to struction of watercourses have had de- • calculate the loading of nutrients teriorating effects in many ways. Ulti- and harmful substances origi- mately the loading reaches coastal wa- nating from different sources ters and affects the coastal zone. Espe- • assess the effects of loading on cially the shallow Finnish coastal zone chemical and biological water is in many respects sensitive to pollu- quality in different coastal areas tion and eutrophication. Widespread • assess changes in the state of deterioration of the ecological status of coastal waters during the 1990s surface waters and nutrient loading and reasons for the changes into coastal waters throughout Europe • evaluate phytobenthos and was highlighted by the European En- macrozoobenthos as a measure vironment Agency (EEA) in “Europe of the state of coastal waters Environment report” in 1999, “the Do- • evaluate changes in fish popula- bris+3” -report, Environmental signals tions and fisheries. 2000 and in a report of Nutrients in European ecosystems. The report is based on the results of On the other hand, the increasing different monitoring programmes, demands for cleaner and more utilisable loading statistics and studies concern- water quality and healthy ecosystem func- ing the state of Finnish coastal water tions are a frequently expressed concern areas. In this report data and informa- everywhere and at all levels in Europe. tion have been collected using the nation- Water protection measures based on sound al data bases in which the monitoring ecological information are urgently need- data is stored and maintained. In the case ed in all countries. Improvement of the of macrozoobenthos the information is ecological status of coastal waters and mainly based on the results of the re- conservation of coastal areas are also cipient control studies. The informa- required by the EU Water Policy Direc- tion on harmful substances is based on tive and the Habitats directive as well national monitoring, recipient control as by many international agreements, data and on specific studies. In order such as the HELCOM convention, the to obtain the relevant data on phytob- Ramsar convention and the Conven- enthos, available published reports and

tion on biodiversity. scientific articles were evaluated. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 7 1.2 Coastal water ministration for research and also by the international com- monitoring munity and monitoring programmes for decision-making The Finnish national monitoring project in environmental control includes: • to study spatial and temporal • Physical/chemical monitoring variations in the state of water of the coastal waters areas and to investigate factors • Biological monitoring of macro- influencing them zoobenthos and phytobenthos • to provide background data for • Monitoring of material inputs to use in other investigations con- the Baltic Sea by Finnish rivers cerning brackish water problems • Monitoring of harmful substanc- • to record the levels and changes es in biota. in concentrations of harmful substances in water, sediments Objectives of the monitoring programme and biota. are: • to produce information on the Organisation of coastal monitoring quality and loading of the Finn- ish coastal waters, and on the The Finnish Environment Institute state of the biological communi- (FEI) coordinates the national coastal ties, for use by the national ad- water-monitoring programme. Region-

Fig. 1.1. Intensive monitoring stations of the Finnish coastal waters: Pohjantähti (1), Hai- luoto (2), Repskär (3), Storbodan (4), Bergö (5), Repo-saari (6), Truutinpauha (7), Seili

(8), Längden (9), Länsi-Tonttu (10), Ängsön (11), Haapasaari (12) and Huovari (13). ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

8 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 1.2. Coastal monitoring stations in Finnish coastal waters.

al Environmental Centres (RECs) car- tensive stations are situated in the out- ry out field observations and sampling. er archipelago waters, not directly in- The analyses are performed mainly by fluenced by wastewater (Fig. 1.1). The the laboratories of the RECs, but in distance between individual stations some cases by the Research Laborato- may be some hundreds of kilometres. ry of FEI. The results are kept in the Two principles have been followed Water Quality database (PIVET) of the when locating the stations: 1) the sta- Finnish Environment Institute. The tion should represent a large coastal zoobenthos monitoring is carried out water body which is quite clean and 2) in co-operation with the Finnish Insti- sampling must be possible without tute of Marine Research (FIMR) and the unreasonable efforts. University of Helsinki. The samples for The other 94 coastal stations are the monitoring of harmful substances located more or less evenly through- are taken by the RECs and analysed by out the territorial zone (Fig 1.2). Most the Research Laboratory, University of of them are at sites not directly influ- Jyväskylä. Both FEI and the RECs are enced by wastewater. It is planned that responsible for reporting. this program, together with local pollution monitoring based on the Water Act and supervised by the RECs, and Geographical coverage the open sea monitoring carried out by FIMR, will provide a basis for evalua- The national network of coastal moni- tion of water quality throughout the toring stations covers the entire area of full range from the vicinity of pollu-

Finnish territorial waters. Thirteen in- tion sources to open sea areas. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 9 Fig. 1.3. Monitoring stations of river loading.

National monitoring of zoob- However, the river Vuoksi Basin is not enthos is carried out at two stations included in this figure because it dis- which are located in Tvärminne on the charges via Russia to the Gulf of Fin- SW coast of Finland, where local pol- land. The areas of large river basins lution is very low (Fig 1.1). The strate- (more than 10 000 km2) account for 75% gy is to analyse natural fluctuations in of the total catchment area whereas the populations of the most important ben- reminder comprises coastal rivers with thic species. These provide background catchment areas less than 5 000 km2. information for evaluating trends in zoobenthos in polluted areas, which is Current sampling frequency included in recipient control monitoring programmes. Biological material is The thirteen intensive stations are sam- collected at eight areas along the Finn- pled 16 to 20 times per year. The strat- ish coast. The areas represent both pol- egy is to follow the annual cycle of the luted and clean areas. water ecosystem of the main water Regarding the coverage in the riv- bodies. The other 94 stations are sam- erine monitoring, the whole area gath- pled only twice a year, at times when ering the rain waters to rivers must be the water body is in steady state in Feb- taken into account. The catchment area ruary/March and in July to September; of Finnish coastal waters totals about biological variables are measured only 250 000 km2, of which monitored riv- in the open water period. This makes

ers comprise about 90% (Fig. 1.3). it possible, with the aid of the other ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

10 ○○○○○○○○○○○○○ The Finnish Environment 472 programmes, to obtain a comprehen- sive areal picture of water quality. National zoobenthos monitoring has continued annually at the two fixed stations in Tvärminne since 1964, but the first records from exactly the same points are available even from the 1920s and the late 1930s. This is the old- est biological time series in the Baltic Sea. Samples are taken twice a year. The autumn records reflect actual population quantities and the spring samples allow estimating of production capac- ities. National phytobenthos monitoring started in 1999 in seven localities and the programme was expanded with two new locations in 2000. The river discharge monitoring covers 30 main rivers (Fig. 1.3). The monitoring was started in 1970 for nutrients and organic matter and in 1982 for heavy metals. However, comparable and reliable analyses for heavy metals were not available until the introduction of ICP (Inductively Coupled Plasmamass Spectrometry) in 1994. Since 1985 the sampling has been ar- ranged according to the variation in the Fig. 1.4. Monitoring stations of atmospheric water flow of each river, sampling fre- deposition. quency of water quality variables usually being 12 times per year. Water flow is measured daily from each of the riv- Atmospheric deposition on lakes ers. The annual material loads via riv- is measured from thirty background ers are obtained by multiplying the stations which are located in the river mean monthly concentrations by the catchment areas (Fig. 1.4). Nutrient monthly flow and summing up the concentrations are analysed from inte- monthly loads. grated monthly samples of rain water. Monitoring of harmful substanc- Precipitation measurements are ob- es has shown that trends in concentra- tained from the Finnish Meteorologi- tions of harmful substances in biota cal Institute. Atmospheric deposition develop very slowly. This fact and the on lakes is calculated by multiplying heavy costs of analysing organic com- specific deposition by the surface area pounds have resulted in the present of lakes. frequency of sampling. Samples are In Finnish coastal monitoring, the taken in autumn and analysed annu- methods are adapted from HELCOM ally by a rolling system of three years: guidelines with some exceptions, e.g. benthic specimens are sampled in the chlorophyll a which is analysed using first year, coastal fish in the second and Finnish standard methods.

open sea fish in the third year. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 11 Variables measured 1.3 International Physico/chemical variables framework Temperature, Conductivity, Salinity, Oxygen concentration and %-satura- HELCOM monitoring is well estab- tion, pH, Turbidity, Solid substances, lished and has been operated since

Colour, Tot-N, NO3 + NO 2, NH4-N, Tot- 1979 when physical, chemical and bi-

P, P O 4-P, SiO2, Fe, OrgC/TOC. ological variables were first measured. Under the new revised Helsinki Con- Biological variables vention in 1992 the obligation of mon- Chlorophyll a, Phytoplankton species itoring of coastal waters was included, composition and biomass, Zoobenthos and countries are obliged to report the species composition, abundance and data to the Commission. The Environ- biomass. Macroalgae species composi- mental Committee is conducting a har- tion, coverage and depth ranges. monised coastal monitoring programme (CMP) which also includes Harmful substances the monitoring of Baltic Sea Protected Hg, Cd, Cu, Pb, Zn, Cr, Mn, Co, Chlo- Areas (BSPA). The coastal monitoring rinated hydrocarbons, Chlorinated programme is completed and it in- phenols, Anisols and veratrols, Toxa- cludes a programme description and phene, EOX, extractable organic halo- technical annexes. All the different pro- gens, PAH, polyaromatic hydrocar- grammes should be integrated into a bons, Dioxins and furans, Coplanary common structure and therefore the PCBs. Cooperative Monitoring in the Baltic Marine Environment COMBINE was established in 1999. The aims of COM- Quality assurance BINE monitoring are to identify and quantify anthropogenic discharges and Many laboratories involved in the coast- activities in the Baltic Sea, against the al monitoring have accreditated their analytical methods. In the area of coastal and background of the natural variations in open sea monitoring, FIMR (Finnish In- the system, and to identify and quan- stitute of Marine Research) has accredi- tify changes in the environment occur- tated also sampling. Accreditation, based ring as a result of regulatory actions. on internationally agreed criteria, is an instrument to provide confidence in the technical competence, impartiality and integrity of the bodies. Personal certifica- tion of the individuals in charge of sampling is in progress according to international recommendations and will soon be completed (Niemi et al. 2000). The aim is that in the near future all the laboratories involved in sampling and analysis of data will have certified individuals in charge of sampling and accreditated methods in

analytical work. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

12 ○○○○○○○○○○○○○ The Finnish Environment 472 Main characteristics of

Finnish coastal waters

○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 2

When considering the marine water The remarkable feature of the northern masses near the Finnish coast, the Bal- Baltic Sea is its relatively wide annual tic Sea can be divided into two major seawater temperature range. The Bal- bodies, the Gulf of Finland and the tic is a cold sea and its temperature Gulf of Bothnia. The Gulf of Finland is varies between 0 and 20 °C. Freezing, a direct extension of the Baltic Proper, ice cover and the duration of the ice and the combined effects of the large depend mainly on the meteorological fresh water inflow to the eastern end conditions, and may vary considerably and the water exchange with the Bal- in different years. The Bothnian Bay is tic proper lead to strong salinity gradi- normally completely covered by ice by ents. In the long term, on a basin-wide January. Generally, complete ice cover- scale, the overall water circulation in age also occurs in the coastal zone the Gulf of Finland is anti-clockwise, down to the Åland Sea and along the resulting in a westward transport along Gulf of Finland. The ice in the coastal the Finnish coast. Locally the currents zones is normally stationary. The thick- are determined by the coastal mor- ness of the ice in the Bothnian Bay is phometry, wind conditions, water lev- about 50–80 cm and it may occur for el changes and freshwater inputs. 150–180 days, for more than 100 days The Gulf of Bothnia (including the with a maximum thickness of 50 cm at Bothnian Bay, Bothnian Sea, Åland Sea the southern border of the Gulf of Both- and Archipelago Sea) has two major nia, and for 30–40 days (25–30 cm) in basins and two larger archipelago are- the Gulf of Finland. The salinity of the as in the northern and southeastern seawater varies between 4 and 5 psu parts (Fig. 2.1). The northern (Bothni- seasonally. Surface waters may become an Bay) and southern basin (Bothnian rather warm in summer, temperatures Sea) are separated by a shallow sill, the of 16–17 °C being frequent in August Northern Quark. Inflow of freshwater over large areas of the Baltic, while in from numerous rivers and from precip- shallow bays temperature of 20 °C may itation causes relatively low salinity of occasionally be reached. the area. There is no tide in the Baltic Sea and irregular fluctuations in the Baltic water level occur mainly in response to the changes in barometric conditions Table 1. Division of sea areas with their catchment area ex- and associated changes in wind force 2 pressed as km . and direction. An underlying seasonal Area Total Finnish area pattern exists. In general, water level follows the pattern of being low in Gulf of Finland 412 900 54 000 spring (March-April) and rising grad- (without Vuoksi) ually, being highest in autumn. In some Archipelago Sea 9 000 9 000 years, water level is high in spring and Bothnian Sea 215 910 39 300 decreases in summer for a short peri- Bothnian Bay 113 620 146 000 od of time. Later in the autumn water

Total 248 300 level rises. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 13 Permanent salinity stratification is the dominant feature of the Baltic hydrography. The freshwater input causes surface water to be less saline than the deeper and bottom waters derived from the subsurface flows. The surface layer is separated from the deeper water by the halocline. However, there is no permanent salinity stratification in the Gulf of Bothnia. Surface salinity varies from over 6 psu in the western parts to around 3 psu in the eastern regions of the Finnish part of the Gulf of Finland. The South coast of Finland is an upwelling area because the more saline Atlantic water after a saline water pulse will eventually surface by the southern coast of Finland. In a small scale, upwelling can occur also locally. Westerly or northerly winds push coastal waters away from the shore and draw deeper waters to the surface. This local upwelling can be detected as cooling of the surface waters and as increased nutrient and salinity values. The shoreline length of the Finn- ish mainland is ca. 6 000 km. Howev- er, this would increase to almost 46 000 km if the fragmented archipelago were Fig. 2.1. The sea areas around Finland and locations of the main munici- included. Finland has ca. 73 000 islands pal and industrial centers on the Finnish coast. and 52 600 of these are small, less than one hectare in size. The most island- rich sea area is the Archipelago Sea, in with 22 000 islands and a total shore 12 000 km. A mosaic of islands and skerries of varying size dominate the Finnish coastal area. The coastline mainly consists of bedrock, although inner parts of the archipelagoes and bays are sheltered enough for the deposition of fine material. On the shores of the islands underwater rock does not reach a great depth and forms only a narrow zone on which attached algae

can grow. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

14 ○○○○○○○○○○○○○ The Finnish Environment 472

Loading of pollutants

○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 3

Pirkko Kauppila, Markku Korhonen, Heikki Pitkänen, Kaarle Kenttämies, Seppo Rekolainen and Pekka Kotilainen

3.1 Nutrient loading and were the main source of N load, accounting for ca. 40% of the total fluxes its source apportionment and 85% of the point source load of N (Figs. 3.4, 3.5). However, in 1998 the During 1991–1996, Finnish coastal wa- municipal load of N in the capital re- ters received annually on an average gion reduced to half from its level in 4 090 t of P and 74 000 t of N from or 1997, due to the introduction of en- via the Finnish territory (Table 3.1). The hanced denitrification in the sewage fluxes varied considerably from year to treatment plants (Pesonen 1999). This year depending mainly on hydrological decreased the total point-source load conditions. In the periods of high run- of N to the Gulf of Finland by ca. 30 %. off, nutrients are abundantly leached Industry, especially pulp and paper from soil, which increases the loads orig- industry, was the main source of the P inating from diffuse sources and natu- load (46% of point source loading) in ral leaching. The greatest nutrient loads the Bothnian Bay (Fig.3.5). (4 600 t of P and 97 000 t of N) in the The contribution of the nutrient decade were received in 1992 and small- load from fish-farming was significant est (3 100 t of P and 65 000 t N) in 1997. only in the catchment of the Archipel- The total fluxes of nutrients origi- ago Sea, where it accounted about 15 nated from various sources: diffuse and 10% of the inputs of P and N re- and point-sources, atmosphere and spectively (Table 3.1, Figs 3.3, 3.4). This natural leaching. Agriculture was the contribution becomes more pro- main anthropogenic source of loading, nounced when considering only the accounting for one third of the total point-sources: more than 70 and 30% fluxes of P and N respectively (Table of the loads of P and N were originat- 3.1, Figs. 3.3, 3.4). In the catchment of ed from fish-farming (Figs. 3.5, 3.6). In the Archipelago Sea, its contribution summertime, the contribution of point- was even higher: ca. 50% of the nutri- source loading is usually more impor- ent loading. However, in summertime tant than diffuse loading (Pitkänen the direct eutrophying effect of agricul- 1994). Moreover, the eutrophying effect tural load was not so pronounced be- is further increased by the facts that cause under normal hydrological con- practically the whole load enters the ditions nutrient leaching from the lake- sea area during the growing season and poor catchments of small agricultural nearly all of the load is bioavailable for rivers mainly occurs during spring and the growth of algae (Pitkänen 1994). August (Pitkänen 1994). The P load from scattered dwell- Point-source loading (industry, ings clearly exceeded the municipal municipalities and fish farming) was load, while its contribution for N flux- responsible for 15 and 20% of the total es remained insignificant. Scattered fluxes of P and N respectively (Table dwellings accounted about 10% of the 3.1, Figs. 3.3, 3.4). In the catchment of total fluxes of P in the Finnish coastal

the Gulf of Finland, municipalities catchment, where about 570 000 inhab- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 15 Fig. 3.1. Scematic representation of loading by different sources entering Finnish coastal waters directly or via rivers.

Sources of loading tabase. In addition, VEPS uses assessments which are based on mathematical models. Nutrients entering into Finnish coastal wa- The assessment methods have been devel- ters, directly from the coast or via rivers, orig- oped simultaneously with the systems tech- inate from various sources (Fig. 3.1). The nical implementation. Using the available point source loading consists of the efflu- data VEPS assesses the sources, quantity ents from industry, municipalities and fish- and temporal variability of nutrient loads farms (Figs. 2.1, 3.2), while diffuse loading into surface waters. VEPS also calculates originates from non-point sources: mainly nutrient fluxes of monitored rivers and di- agriculture, forestry, scattered dwellings, vides it into different sources. The division atmospheric deposition and natural leach- is based on the assessment of the quantity ing. Nutrient loads via rivers are assumed of the nutrient load in the catchment area. to be carried unchanged into the coastal In large catchment areas VEPS takes reten- waters in lake-poor river basins (Pitkänen tion into account. 1994, Rekolainen et al. 1995). In lake-rich river basins such as in the Rivers Kymijoki, Kokemäenjoki and Oulujoki retention of nutrients must be taken into account.

Budget calculations In budget calculations, annual nutrient fluxes into Finnish coastal waters from different sources were gained by the means of the data base system of VEPS developed by FEI for the estimation and control of nutrient loads into watercourses. VEPS is an a up to date Management and Assessment system for water pollution. VEPS can be used to easily obtain information about nutrient loading, its quantity and sources. The VEPS system has an easy to use user interface, and it has been developed to help re- searchers of the Finnish Environmental Ad- ministration. The VEPS system uses the data base system of HERTTA which includes the point sources database, the surface water Fig. 3.2. Locations of fish farms in Finnish

quality database and the hydrological da- coastal waters in 1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

16 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 3.3. Total load of P (t a -1) from different sources into Finnish coastal waters in 1991– 1996. Note that nutrient loads from Russia and Estonia to the Gulf of Finland and the loads from Sweden to the Gulf of Bothnia have not been included in these calculations. itants lived in year around in houses courses in the northern Finland, the not connected to public sewerage sys- retention of nutrients leaching from tems (Table 3.1, Fig. 3.3). In the catch- forestry soil was generally small. How- ment of the Bothnian Bay, the greater ever, nutrient leaching from soil is pro- load was mainly due to weaker equip- moted by the great percentage of wet- ment for lavatory wastes compared to lands. Considering forestry operations, that in the other main catchments. remedial drainage was the greatest sin- The contribution of forestry, as gle source of nutrient leaching in the well as natural leaching, increased catchment of the Bothnian Bay (Kent- from south to north (Table 3.1). In the tämies and Vilhunen 1999). catchment of the Bothnian Bay, forest- The proportion of forestry practic- ry was the main source of anthropo- es as a source of nutrient loading was genic P load, accounting for nearly 25% greatest to the Bothnian Bay, but fairly of the total P fluxes (Fig. 3.3). Forestry insignificant to the other sea areas re- was mainly practised in the upper garding to both N and P. During 1991- parts of the catchments. Due to the 1996, the mean annual input originat-

small lake percentage of the water- ing from forestry practices was about ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 17 Fig. 3.4. Total load of N (t a -1) from different sources into Finnish coastal waters in 1991– 1996. Note that nutrient loads from Russia and Estonia to the Gulf of Finland and the loads from Sweden to the Gulf of Bothnia have not been included in these calculations.

400 t of P and 3 370 t of N (Table 3.2). 20% of the total fluxes of P and N) and Phosphorus loading decreased during greatest in the catchment of the Both- that time but the same trend was not nian Bay (ca. 40 and 50% of the total found in nitrogen figures. The main fluxes of P and N). reason for this is the almost total ceas- Table 3.2. The estimated mean total phosphorus and total ing of phosphorus fertilization in the nitrogen loads (t a-1) from forestry practices on catch- late 1980s. Instead, the main nitrogen ments into coastal waters in 1991–1996 (Kenttämies and loaders, drainage and felling, have re- Vilhunen 1999). mained on the stable level. The atmospheric nutrient deposi- Main catchments Total nitrogen Total phosphorus tion on lake surface accounted 3% of t a-1 t a-1 the P and 10% of the N inputs (Table 3.1, Figs. 3.3 and 3.4). Natural leaching Bothnian Bay 2152 273 contributed about one third of the to- Bothnian Sea 515 54 tal fluxes of nutrients to Finnish coast- Archipelago Sea 81 7.5 al waters, being smallest in the catch- Gulf of Finland 622 66

ment of the Archipelago Sea (ca.10 and Total 3370 400.5 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

18 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 3.5. Point-source loading of N (t a-1) into Finnish coastal waters by sources in 1997. Note that nutrient loads from Russia and Estonia to the Gulf of Finland and the loads from Sweden to the Gulf of Bothnia have not been included in these calculations.

Total P Municipalities Industry Fish farming

125

96 Fig. 3.6. Point-source loading of P (t a-1) into Finnish coastal waters by sources in 1997. Note that nutrient loads from Russia and Estonia to the Gulf of Finland and the loads from Sweden to the Gulf of 145 Bothnia have not been included in these 92

calculations. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 19 Table 3.1. Loads of P and N (t a-1) to Finnish coastal waters in 1986–90, 1991–96 and 1997. Note the difference in estimating diffuse load in 1986–90 and in 1991–1996/1997. Regarding the load calculations for the period of 1986-90 by Pitkänen (1994), the contributions of forestry, atmospheric inputs and natural leaching are included in the calculations of background load while the load from scattered dwellings is included in the calculations of agricultural load. The correction factor presented by Mäkinen (1998) for the nutrient loads from fish-farming(1) was taken into account for the period of 1995–96/97. The uncorrected values(2) have presented here only to show the trend of nutrient load from fish-farming. Coastal region 1986–90 1991–1996 1997 PN PN PN Gulf of Finland municipalities 160 5286 93 5809 72 5038 industry + traffic 137 738 104 805+24 54 627 fish-farming 2 17 112 15 104 10 70 fish-farming 1 . . 29 165 19 112 agriculture 309 5140 235 4240 . . forestry . . 15 220 . . scattered dwellings . . 86 920 . . atmosphere . . 17 1640 . . natural leaching . . 84 3890 . . background 264 8627 . . . . total 887 19903 664 17705 461 13796

Archipelago Sea municipalities 39 1088 30 1315 20 1032 industry 1.3 189 5 191 2 86 fish-farming 2 56 410 51 386 40 298 fish-farming 1 . . 94 623 92 477 agriculture 379 4050 297 3090 . . forestry . . 4 40 . . scattered dwellings . . 60 330 . . atmosphere . . 2 150 . . natural leaching . . 57 1290 . . background 105 1332 . . . . total 580 7069 550 7030 511 7734

Bothnian Sea municipalities 46 1223 28 1616 30 1662 industry 115 503 43 473 41 360 fish-farming 2 19 147 17 136 13 103 fish-farming 1 . . 34 212 25 165 agriculture 433 5770 360 6110 . . forestry . . 32 320 . . scattered dwellings . . 85 620 . . atmosphere . . 22 1420 . . natural leaching . . 177 5010 . . background 437 10004 . . . .

total 1050 17647 782 15781 653 16789 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

20 ○○○○○○○○○○○○○ The Finnish Environment 472 Coastal region 1986–90 1991–1996 1997 PN PN PN

Bothnian Bay municipalities 76 2113 37 2209 39 2495 industry 182 1713 115 1518 80 1351 fish-farming 2 4.5 35 4 32 3 26 fish-farming 1 .. 851642 agriculture 565 9040 377 6220 . . forestry . . 506 860 . . scattered dwellings . . 139 1100 . . atmosphere . . 92 3870 . . natural leaching . . 815 17550 . . background 1501 21443 . . . total 2329 34344 2090 33378 1798 31112

Total municipalities 321 9710 188 10949 175 9332 industry + traffic 435 3143 268 2987+24 164 2286 fish-farming 2 97 704 89 669 86 665 fish-farming 1 . . 165 1043 163 1063 agriculture 1686 24000 1270 19660 . . forestry . . 559 1440 . . scattered dwellings . . 370 2970 . . atmosphere . . 133 7080 . . natural leaching . . 1133 27740 . . background 2307 41406 . . . . total 4846 78963 4086 73903 3424 69430 Footnote: Nutrient loads from fish-farms were estimated by mass balance calculations based on the amount and nutrient content of the feed, the amount of produced fish and the type of the plant. On the basis of the recent information on the amounts of feed sold and the weighted means of the nutrient contents of feeds in 1995 and 1996, the loading of phosphorus would be 90% and the loading of nitrogen 60% greater than was originally reported by fish farms (Mäkinen 1998).

3.2 Trends in the nutrient load of P by about 16% was mainly due to water protection measures in indus- loads in 1985–98 try and municipalities. However, in the Archipelago Sea no clear change in The average annual nutrient fluxes to nutrient fluxes could be observed, Finnish coastal waters in the 1990s were mainly due to equal level of runoff be- smaller than in the late 1980s (Table 3.1, tween the two study periods. Fig. 3.7). This is partly due to smaller As for P, the municipal and indus- water flows to the sea areas and partly trial load has decreased by 60% since due to changes in loading from differ- the mid 1980s, mainly due to more ef- ent sources (Figs. 3.7–3.10). The total ficient purification of waste waters load of N decreased by 10% from the (Fig. 3.8). The reduction of the munici- level of the late 1980s, which is simply pal load actually started already in the explained by the smaller water flow in 1970s after the introduction of Fe/Al pre- the 1990s because the point-source cipitation in the purification plants. The loading of N actually slightly increased next strong decrease in the load of P in

during that time. The decline in the the early 1990s was due to the introduc- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 21 Fig. 3.7. Trends of point-source loads of N and P into Finnish coastal waters in 1985–1997.

tion of active sludge method in pulp ever, the direction and the slope of the and paper industry, and the centraliza- trend varied in each main catchment: tion of municipal waste water treat- In the Gulf of Finland, Archipelago Sea ment, especially in the Helsinki region. and Bothnian Sea the reductions were Regarding point sources, the total 15, 22 and 28% respectively, and the loads of N decreased by 10% since the level of the mid 1980s was achieved

peak in the early 1990s (Fig. 3.8). How- again in 1996–97. On the contrary, in ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

22 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 3.8. Trends of the total fluxes of N and P into Finnish coastal waters in 1985–1997.

the Bothnian Bay the load has even in- increase in the number of households creased (24%) since the mid 1980s al- connected to sewer systems. The re- though this trend levelled off in the late duction in the 1990s was mainly due 1990s. The increase in the 1980s (and to centralization of municipal treat- in the Bothnian Bay also in the early ment and better control in the treat- 1990s) was mainly due to municipal ment plants of pulp and paper indus-

loading. This, in turn, resulted from the try. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 23 The increase in the loading of N and P from fish farming by more than 70% since the mid 1980s was a consequence from the intensified production of rainbow trout in cages. However, the load started to reduce in the early 1990s partly due to diminished production, and partly due to protection measures by optimazing the content of feed, and organizing feeding. By 1997 it had decreased by 30% from the level of the early 1990s. The potential load (retention in lakes not included) from forestry practices in the catchment area of the Bal- tic Sea had a decreasing trend in phosphorus leaching but fairly stable level in nitrogen load. The main cause to this is almost the total ceasing of phosphorus fertilization in late 1980s. Instead, the main nitrogen loaders, drainage and felling, have remained on the stable level. Targets set in Ministry Declaration in 1988 for decreasing industrial and municipal loading of P to Finnish coastal waters was succeeded in the 1990s. On the contrary, the load of N from agriculture, municipalities and industry were not remarkably declined. A new target has been set to decrease the load of nutrients by about 50 % from all sources of nutrient loading by the year 2005.

Control of agricultural pollution Before Finland joined the European Un- ion (EU) and accepted its Common Agri- cultural Policy (CAP), its environmental policy and management of agriculture were mostly based on information and education by agricultural and environmental authorities and extension servic- es. Only limited financial incentives were available for farmers, mostly directed towards investments for manure storage. No direct legislation existed for controlling agricultural pollution, except an environmental tax added to fertilizer prices for a few years in the 1990s, which led to a reduction in fertilizer use.

Fig. 3.9. Mean annual water flows (MQ, m3 s-1) and riverine fluxes of P

into Finnish coastal waters in 1970–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

24 ○○○○○○○○○○○○○ The Finnish Environment 472 A massive financial incentive programme in accordance with the EU’s Agri- Environmental Support Scheme was launched in Finland in 1995, when Fin- land joined the EU. Through this programme, farmers are paid to adopt environmentally sound management practices. In 1998, more than 80% of Finnish farmers participated in the programme. Briefly, to be eligible for support, farmers must simultaneously achieve the following on their farms: • Farm environmental management plans must be prepared. • The maximum levels of fertilization plus manure application must not be exceeded. • Manure must be appropriately stored and may not be spread on frozen soil or on snow. • Livestock density may not exceed 1.5 livestock units ha-1. • Buffer strips (1–3 m in width) must be established on the sides of main ditches and watercourses. • Pesticide spraying devices must be tested by an authorized agency, and pesticides may be applied only by a person who has been trained in their use. • At least 30 % of arable land must be covered by crops or crop residues (reduced tillage techniques) during the winter in southern Finland.

Implementation of the EU’s Agri-Environ- mental Support Scheme in Finland has led to significant changes in agricultural practices resulting in more environmentally sustainable agriculture. The implementation of the Nitrate Directive in Finland sets upper dose limits for chemical fertilizer and manure spreading, and also time limits for manure spreading (no spreading al- lowed on frozen soil or on snow cover); however, the undertakings according to the directive are less demanding than the requirements of the Finnish Agri-Environmen- tal Scheme. With more than 80% of Finnish farmers participating in the scheme, it can be expected that only a minor general reduction in nitrate losses can be achieved via implementation of the Nitrate Direc- tive. However, it may have local impact in areas with intense animal husbandry.

Fig. 3.10. Mean annual water flows (MQ, m3 s-1) and riverine fluxes of

N into Finnish coastal waters in 1970–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 25 Atmospheric deposition The natural or background All the pollutants that are released into leaching of N and P atmosphere must at some time return to The background load is a figure for the the earth again. This can occur in two natural leaching from a catchment area ways: gaseous and particle-borne sub- that is not affected by human activities stances can be transferred directly to the (HELCOM 1998). All anthropogenic nu- ground, to water surfaces or to vegetation, trient sources, both point and diffuse ones, while substances scavenged by cloud or have to be separated from natural leach- rain drops reach the earth’s surface in pre- ing. Typical anthropogenic diffuse sourc- cipitation. The first is called dry deposi- es of nutrients are scattered dwellings, ag- tion and the second wet deposition. riculture, forestry and anthropogenic part Atmospheric deposition of inorganic of airborne nutrient load. The estimation nitrogen consists of oxidised nitrogen of natural leaching is based on specific co- (NOx) and reduced nitrogen (ammonium, efficients obtained from the monitoring NHx). Agricultural activities are the pre- programmes of small drainage basins dominant source of ammonium deposi- (Kauppi 1979, Rekolainen 1989). tion while most of nitrogen oxides emis- The natural leaching of nitrogen and sions are generated in the combustion of phosphorus from pristine, untouched ter- fossil fuels (e.g. as exhaust gas of traffic). restrial ecosystems is not very well In the mid 1990s, one third of total dep- known, even if its importance in the osition of ammonium and 15% of that of source apportionment of total nutrient nitrogen oxides to Finnish area originat- load of rivers is large, especially in the ed from Finnish sources (Ministry of the northern rivers. Special problems arise Environment 1998). The main part of dep- when calculations are needed about the osition was gained by long range trans- natural leaching from fields, because lit- port from other European countries, Rus- tle is known of the quality of their origi- sia being responsible for below 10 % of nal, past ecosystems. The majority of con- the nitrogen deposition to Finland. The temporary fields in Finland are supposed predominant contributors of nitrogen to represent forest types on fine textured, deposition to the Baltic sea area are Ger- nutrient rich soils before taking into cul- many, Poland, Denmark and Sweden (Bar- tivation. However, about the third of fields tnicki et al., 1998). Finnish emissions con- are former sea or lake bottom soils or peat- tribute 16% of nitrogen deposition to the lands (Kähäri et al. 1987) without any for- Gulf of Bothnia and 10% of nitrogen dep- ested phases in the past time. osition to the Gulf of Finland. About half The airborne load of nitrogen and of total atmospheric nitrogen deposition phosphorus are not easily separable from to the Gulf of Bothnia and Gulf of Fin- natural leaching, and may increase the land comes from outside the Baltic coun- “natural” background level. For example tries. in 1995 annual precipitation of inorganic Modelling calculations of atmospher- nitrogen was about 1 000 kg km-2 a-1 in the ic deposition to the Baltic Sea suggest that south and 200 to 300 kg km-2 a-1 in the nitrogen deposition has decreased by northern Finland (Barret and Berge 1996). about 20% from 1986 to 1996 (Bartnicki et Total phosphorus deposition was about al.,1998). This is mainly due to the gener- from 8 to 12 kg km-2 a-1 in the southern al decline in nitrogen emissions in areas Finland and from 3 to 6 kg km-2 a-1 in the contributing to deposition to the Baltic sea, northern Finland (Järvinen and Vänni most notably in Germany, Poland, Den- 1997). The high inorganic nitrogen loads mark, Estonia, Latvia and Lithuania (Tar- during snow melt time in spring clearly rason and Schaug, 1999). Nitrogen emis- show the importance of airborne loading sions in Finland and Sweden have not (Anderson and Lepistö 1998). However, dropped considerably during the period contemporary calculations of background 1986-1996. In the Russian Federation the load do not separate airborne load and reported emissions of reduced nitrogen natural leaching. The share of natural and have decreased by 40% but simultaneous- anthropogenic nutrients in precipitation ly the emissions of oxidised nitrogen have are uncertain, too, and in calculations only increased, the net effect being a 16% de- wet and dry deposition right on lake or

crease in total nitrogen emissions. sea surfaces are included. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

26 ○○○○○○○○○○○○○ The Finnish Environment 472 3.3 Loading of organic 3.4 The loading of matter and trends in harmful substances 1985–97

In 1997, the point source load of organ- Several harmful contaminants enter ic matter (measured as BOD7) to Finn- Finnish coastal waters as effluents from ish coastal waters was 17 600 t, which industry, as diffuse loads, and via the load was mainly discharged to the atmosphere. The groups of compounds Bothnian Sea and the Gulf of Finland that the most attentation is given in this (Table 3.3). Industry, woodpro-cessing report are PCBs, DDTs, chlorinated industry, was responsible nearly 80% pesticides, polychlorinated dioxins and of the load. The decrease in the load of furanes (PCDD/Fs), polyaromatic hy- organic matter by more than 70% since drocarbons (PAHs) and heavy metals the mid 1980s was due to the introduc- (Hg, Cd, Zn, Pb, Cr and Cu). Many of tion of active sludge method in wood- the harmful organic compounds origi- processing industy. nate from incomplete combustion

-1 Table 3.3. Point source load of organic matter (BOD7, t a ) to the Finnish coastal waters in 1986–90, 1991–96 and 1997.

BOD7 1986–90 1991–1996 1997 Gulf of Finland municipalities 12751 6588 3661 industry 2841 1858 1576 total 15592 8445 5237

Archipelago Sea municipalities 159 75 63 industry 835 692 759 total 994 767 822

Bothnian Sea municipalities 11888 2772 2655 industry 1348 1405 1057 total 13235 4177 3712

Bothnian Bay municipalities 20224 9137 6507 industry 1393 1336 1273 total 21618 10473 7780

Total municipalities 45023 18572 12886 industry 6417 5290 4665

Total 51439 23862 17551 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 27 (PAHs, dioxins), the disposal and dis- ganic compounds has led to dramatic integration of old condensators, trans- changes in the processes in pulp mills. formers or other electrical equipment The use of elementary chlorine as a (PCBs), or are side products of chemi- bleaching agent has been replaced by cal processes (PCDD/Fs). After the ban chlorine oxide, or other oxygen con- on PCBs and DDTs in Scandinavia, the taining chemicals such as molecular input of these organochlorines into the oxygen, ozone or peroxide. In addition, northern Baltic Sea has declined, but sewage treatment has been improved not altogether stopped. considerably, with the installations of Over a lengthy period of time the external treatment plants of different sea areas surrounding Finland have designs. Finally most plants have de- been loaded with metals, chiefly from creased their waste-water emissions by metallurgical industry, chemical indus- increased closure of the processes tries and mines. Taking into account (Owens and Lehtinen, 1995). the development of industry it may be assumed that this load was at its heav- iest in the 1960s. For the first time there Hot spots was concern about the danger these emissions represented to the environ- In the hot spot list, specified by HELCOM ment. Though the measurement of Convention in 1992 to decrease deteriorating effluents to the Baltic for recover- emissions at this time was sparse, it can ing the ecologically healthy balance of the still be estimated that the load of mer- sea, 8 out of 134 sites were located in the cury, cadmium, lead and arsenic has Finnish catchment. By now, the number decreased by at least 95% to the Gulf of hot spots in Finland has decreased to 3 of Bothnia during the last 20 years (En- sites, the remaining representing agricultural runoff in the Archipelago Sea, fish- cell-Sarkola et al. 1989). This means farming in the Archipelago Sea and Åland that the situation today is much better Sea and metal industry in the Bothnian than even ten years ago. On the other Sea. hand, it must be remembered that a lot of heavy metals and other persistent hazardous compounds have been de- posited and stored in the Finnish coast- Accumulation of pollutants al area, which is also evident in the elin biota evated concentrations in sediment and Pollutants are usually spread over vast biota. areas by currents and hence the immedi- The direct load from industries ate effect on the biota is often small due through waste water is not the only to the large dilution factor. The direct effects of toxic organic pollutants, or heavy input of heavy metals into the sea en- metals, in the sea may remain unnoticed vironment. Heavy metals find their for a long time until becoming apparent way into the sea environment through when top predators such as seals or salm- municipalities, by river transportation on are affected. (Table 3.4) and by deposition from the Not only the top predators, but also atmosphere. filtering organisms such as the common mussel (Mytilus edulis), are able to accu- The pulp and paper industry has mulate large quantities of heavy metals. historically been considered a signifi- Toxic effects in this mussel are usually dis- cant contributor of pollutants to the cerned as histopathological changes but environment. The bleaching of pulp may also result in death if exposure is long with chlorine can produce a great enough. Since the common mussel is a popular food for flatfish, cod and eider, number of chlorinated organic com- which in their turn are consumed by hu- pounds. From the end of the 1970s, the mans, heavy metals may very well end up public concern about the potential haz- accumulated in humans.

ard of the discharge of chlorinated or- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

28 ○○○○○○○○○○○○○ The Finnish Environment 472 Table 3.4. The total load of heavy metals (t a-1) into Finnish coastal waters in 1995. Contaminant rivers municipalties industries total Gulf of Finland Mercury 0.07 0.01 0.0 0.08 Cadmium 0.13 0.006 0.0 0.136 Chromium 17 . 0.005 17 Copper 27 1.53 0.039 28.6 Lead 6 0.29 0.034 6.3 Zinc 89 6.38 0.067 95

Archipelago Sea Mercury 0.04 0.007 0.0 0.011 Cadmium 0.16 0.004 0.0 0.16 Chromium 14 . 0.003 14 Copper 14 0.36 0.099 14.4 Lead 4.3 0.11 0.075 4.3 Zinc 75 2.07 0.011 77

Bothnian Sea Mercury 0.09 0.002 0.02 0.11 Cadmium 0.8 0.001 0.07 0.15 Chromium 26 . 14.4 40.4 Copper 2.6 0.26 0.95 3.8 Lead 11 0.05 1.51 12.5 Zinc 192 1.07 38 231

Bothnian Bay Mercury 0.56 0.002 0.02 0.58 Cadmium 1.1 0.002 0.08 1.1 Chromium 41 . 3.44 44.4 Copper 42 0.38 0.16 41.5 Lead 10 0.07 0.01 10.1 Zinc 200 1.64 7.7 209

Total Mercury 0.76 0.021 0.04 0.78 Cadmium 2.19 0.013 0.15 1.42 Chromium 98.0 . 17.8 115.8 Copper 85.6 2.19 1.25 88.3 Lead 31.3 0.52 1.63 33.2

Zinc 556 11.2 45.8 612 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 29 Hydrography and

oxygen conditions

○○○○○○○○○○○○○○○○○○○○ 4 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

Heikki Pitkänen, Pirkko Kauppila and Yki Laine

4.1 Salinity Vertical stability Horizontal distribution The general hydrography of the Baltic Sea causes the well known vertical sa- The surface and bottom open sea salinity stratification for the Gulf of Fin- linities showed the typical increasing land. The salinity difference between gradient in the Gulf of Bothnia from the mixed surface layer and the near- the Bothnian Bay (2 to 4 psu) via the bottom waters was up to 3 psu in sum- Bothnian Sea (5 to 6 psu) to the Archi- mer and 2 psu in winter (Figs. 4.2 and pelago Sea (6 to 6.5 psu) and in the Gulf 4.3). In the Gulf of Bothnia the vertical of Finland from the east (4 to 5 psu) to stability is much weaker: in the present the west (5 to 6.5 psu, Fig. 4.1). In the data practically no difference was ob- Gulf of Finland, the wintertime salini- served in winter, whereas mean differ- ties were about 0.5 psu higher than the ences up to 1 psu were detected in the summer ones, reflecting the high fresh- summer data. Due to the influx of sa- water flow from the River Neva (Fig. line water from the North Sea to the 4.2). In the Gulf of Bothnia, the season- Baltic Sea in 1993, the vertical density al variations in surface salinity were stratification has strengthened in the small, except in the NE Bothnian Bay, Gulf of Finland since 1995. which showed very low wintertime Very strong wintertime stratifica- salinities (< 1 psu) over an area of about tions (vertical differences up to 5 psu) 2000 km2 due to the concentration of were observed especially in larger es- river waters just below the ice cover. tuaries (Kymijoki, Karjaanjoki, Uskel- anjoki, Paimionjoki, Kokemäenjoki and Kyrönjoki) as well as in the whole NE Bothnian Bay, which indicates very poor vertical mixing and an extensive spread of river water as a separate layer immediately below the ice in these

areas. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

30 ○○○○○○○○○○○○○ The Finnish Environment 472

Fig. 4.1. Mean bottom layer values for salinity in summers 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 31

Fig. 4.2. Mean surface values for salinity in winters 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

32 ○○○○○○○○○○○○○ The Finnish Environment 472

Fig. 4.3. Mean bottom layer values for salinity in winters 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 33

Fig. 4.4. Mean bottom layer values for oxygen in summers 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

34 ○○○○○○○○○○○○○ The Finnish Environment 472 4.2 Oxygen coastal basins the conditions have been particularly poor since the mid 1990s. In winter, the oxygen conditions have In the open Gulf this can be explained been good in the whole open sea area (in addition to autochtonous produc- and also in most parts of the coastal wa- tion caused by large nutrient inputs) ters. Reduced saturation values (below by the inflow of saline water which 70%) were observed only in some deep entered the Gulf in 1995. parts of the open Gulf of Finland and in very restricted coastal areas (mostly Anoxic bottoms small bays or estuaries). In summer the conditions were clearly poorer espe- Due to the increased sedimentation cially in the deep open Gulf of Finland, and decomposition of organic matter, where mean saturation values from 30 oxygen will be used up and anoxic con- to 60% were common. In the coastal ditions can occur in the water column waters mean values below 50% were and especially in the bottom layers. obtained for several coastal basins and Shortage of oxygen and therefore in- estuaries both in the Gulf of Finland crease in the production of hydrogen and in the Archipelago Sea (Fig. 4.4). sulphide in the sediment has negative The oxygen conditions of the effects on the fauna and flora. Bottom- 1990s were generally, both in winter dwelling animals suffer and fish either and in summer, better than those of the die or escape the affected area and in- earlier assessment period (1979–83), creased nutrient concentrations also mainly due to weakened salinity strat- cause changes in aquatic vegetation. ification and decreased loading of or- Several semi- enclosed bottom areas ganic matter (BOD7) from the coast. with reduced sediment surface have However, despite the decreased load- been detected in the coastal Gulf of Fin- ing and vertical stability in the Gulf of land in the late 1990s (Fig. 4.5). The rea- Finland, the conditions there were at son for the phenomenon is partly an- least as poor as ten years earlier. In cer- trophogenic (external loading) and tain enclosed basins, oxygen concen- partly natural (coastal topography, trations were even lower than in the physical stratification). Longer time- 1980s indicating some kind of cumu- series reviel that locally reduced bot- lative effects of loading in these areas. toms and internal loading have caused In the eastern Gulf of Finland in the eutrophication at least since the 1970s.

Fig. 4.5. Anoxic bottom sediments in the Gulf of Finland in August 2000. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 35 Internal nutrient loading The importance of iron in phosphorus binding and Normally it is assumed that loading is so- as a buffer for hydrogen sulfide called external loading, which can be defined as loading into the ecosystem from in marine sediments outside e.g. via rivers, from the atmos- The classic model explaining release of phere or from sewage treatment plants. phosphate from sediment to water is However, in the Baltic Sea the phenome- based on the Fe cycle in the sediment. non of internal loading may occur. This is Solid Fe(III) oxides are reduced to dis- defined as loading taking place inside the solved Fe(II) ions and after this reduction aquatic ecosystem, e.g. release of phos- Fe bound phosphate is released to inter- phorus from bottom sediment to the wa- stitial water of the sediment. When re- ter column in anoxic conditions. Nitrogen duced dissolved Fe(II) is transported to and phosphorus are sedimented as par- the oxic sediment surface it is oxidized ticulate matter on the surface of the bot- back to Fe(III) oxides, which have a high tom. However, all sedimented nutrients capacity to bind phosphate. Thus these are not buried into the sediment. After precipitated Fe(III) oxides can effectively mineralization and chemical processes, prevent phosphate from entering the eu- parts of the nutrients are changed into photic layer of water. Another important dissolved forms, which are transported function of sediment Fe(III) oxides is to

from the sediment back to water. These block toxic hydrogen sulphide (H2S) en- bioavailable dissolved inorganic nutrients tering from sediment to water. In this ox- originating from sediment constitute part idation-reduction reaction Fe(III) oxides

of the new biological production occur- are reduced and H2S is oxidized to sulfate

ring in the euphotic zone of water. (SO4). ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

36 ○○○○○○○○○○○○○ The Finnish Environment 472

Nutrients

○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 5

Heikki Pitkänen, Pirkko Kauppila and Yki Laine

5.1 Spatial distributions Neva and St. Petersburg and due to the estuarine hydrography of the Gulf. How- of phosphorus and nitrogen ever, the east-west gradient has weak- 5.1.1 Winter ened in the 1990s, possibly due to decreased loading from the River Neva. The late winter concentration distribu- Some clear changes in the open tions of both total and inorganic N and sea nutrient distributions can be found P indicate the trophic conditions and between the present period of study sources of nutrients around the Finn- (1991–98) and 1979–83, the period of the ish coast due to the negligible activity previous corresponding report (Pitkä- of primary producers (Figs. 5.1a,b; 5.2; nen et al. 1987). The most extensive is 5.3a,b; 5.4a,b). The winter level of inor- the increase in the level of P in the open ganic nutrients also directly controls the Bothnian Sea, whereas in the eastern level of the spring algal bloom. This Gulf of Finland a decrease of ca. 20% has means that in the Gulf of Finland where taken place in the average level of TP, the nutrient levels are highest, the spring probably reflecting the decreased load bloom of phytoplankton, as well as the from the River Neva – St. Petersburg summertime productivity, is also most region in Russia (Pitkänen et al. 1997). pronounced, whereas in the P-limited In coastal waters, the most strik- Bothnian Bay both the concentrations ing changes between the early 1980s and of P and the general productivity dur- the 1990s were the increase in the area of ing the growth period are lowest. TN concentrations exceeding 500 mg m- Both in the Gulf of Finland and in 3 in the middle and inner Archipelago Sea the Gulf of Bothnia, clear west-east and and in parts of the coastal Bothnian Bay. south-north gradients prevail, where- Regarding the changes in P distribution, as in almost all loaded coastal regions the area of TP concentrations exceed- an open sea – coast gradient can be ing 40 mg m-3 has decreased off the found. In the Gulf of Bothnia the open larger point-source loaders in the Both- sea gradient for both total and inorgan- nian Sea (Uusikaupunki, Rauma, Pori, ic P is, in contrast to N, from north to Kaskinen, Vaasa), most probaly due to south due to the effective chemical pre- the decreases in the municipal and in- cipitation of P with iron compounds in dustrial (pulp and paper industry) the Bothnian Bay (cf. Voipio 1969). This loading of P to these coastal water are- leads to low concentrations of bioavail- as (Figs. 3.8). able P in this sea area despite the volu- The winter distributions of both minous nutrient inputs from several TN and DIN clearly reflect the inputs large rivers (Fig. 3.6). from rivers and larger towns as the A clear west-east gradient in N main coastal sources of N. Due to the and P compounds is observable both permanent ice cover in coastal waters in the open sea and in Finnish coastal in February-March, water areas with waters outside local loading sources, elevated concentrations (more than 500 due to the strong nutrient loading to mg TN mg m-3 or 200 mg DIN mg m-3)

the easternmost Gulf from the River in the surface layer extended further ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 37

Fig. 5.1a. Mean surface values for total phosphorus in winter 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

38 ○○○○○○○○○○○○○ The Finnish Environment 472

Fig. 5.1b. Mean bottom layer values for total phosphorus in winter 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 39

Fig. 5.2. Mean bottom values for total nitrogen in winter 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

40 ○○○○○○○○○○○○○ The Finnish Environment 472

Fig. 5.3a. Mean surface values for inorganic nitrogen in winter 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 41

Fig. 5.3b. Mean bottom layer values for inorganic nitrogen in winters 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

42 ○○○○○○○○○○○○○ The Finnish Environment 472

Fig. 5.4a. Mean surface values for inorganic phosphorus in winters 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 43

Fig. 5.4b. Mean bottom layer values for inorganic phosphorus in winters 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

44 ○○○○○○○○○○○○○ The Finnish Environment 472 outwards from the coast than in the Bothnian Bay, inorganic N varied be- near-bottom waters. A similar, but tween 50 and 100 mg N m-3 due to the clearly weaker (due to the fixing by clearly P-restricted primary production primary producers) effect can also be (Alasaarela 1980) and the accumula- seen in the summer distributions of N. tion of the extra bioavailable N in the The reason for these phenomena is that water mass. Thus the Bothnian Bay river water is lighter than brackish rather resembles lakes in this respect. coastal water and especially in winter During the 1990s internal loading the mixing of the two water layers is of nutrients caused an increase in the limited because of the lack of wind levels of both TP and DIP in the Gulf shear stress (cf. Alasaarela 1980). of Finland, although external loading to the Gulf decreased during the same period. The reason for this was an ex- 5.1.2 Late summer tensive anoxia at the sediment-water interface in vast areas, especially in the The late summer period (July-Septem- eastern Gulf in 1996 (Pitkänen and ber in the present study) represents Välipakka 1997). Oxygen problems conditions when the growth of algae have also been observed in smaller is usually nutrient (N, P) limited (cf. scale in the coastal waters of the Gulf Tamminen et al. 1996). Thus the sur- of Finland (Fig. 4.5). face concentrations of both inorganic It is possible that the increased N and P were usually low in the open level of P in the southern and south- sea areas (Figs. 5.5 , 5.6), generally near western Archipelago Sea is connected or below the detection limits of the an- to the corresponding increase in the alytical methods (here 2 mg m-3 for Gulf of Finland, because due to the phosphate-P and 5 mg m-3 for both general anti-clockwise circulation sys- ammonium- and nitrate-N). tem, waters outflowing from the Gulf In the coastal waters, the values of Finland tend to turn towards the were in many places at an elevated lev- Archipelago Sea (Helminen et al. 1998). el due to the continuous inputs from Regarding phosphorus, the gener- rivers and coastal point-sources. Typi- al distribution of near-bottom nutrient cally, the areas of increased values of reserves in summer largely resembles DIN and DIP are much smaller in sum- that of wintertime values: lowest in the mer than in winter due to the effective Bothnian Bay and highest in the Gulf fixing of nutrients by primary produc- of Finland (Fig 5.7). In the case of ni- ers in summer and, on the other hand, trogen the situation is somewhat dif- the undisturbed spreading of nutrient- ferent due to the strong accumulation rich river waters under the ice in win- of N in the P-limited Bothnian Bay. As ter. In shallow coastal waters lacking a a result, N concentrations increase permanent thermocline (e.g. smaller from the Bothnian Sea to the Bothnian bays), the nutrient concentrations and Bay, while in the Gulf of Finland there productivity are elevated by the up- is a clear west-east gradient towards ward vertical transport of benthic and the Neva Estuary. near-bottom nutrients. The reasons for the deep water P Clearly elevated concentrations distribution are obvious: the main pro- (more than 10 mg DIP and/or 50 mg cess transferring nutrients from the eu- DIN m-3, Fig. 5.5, 5.6) were observed only photic surface layer to the aphotic near- in restricted areas in the estuaries of the bottom layer is the sedimentation of rivers Kyrönjoki, Kokemäenjoki, Uske- plankton detritus (e.g. Heiskanen 1998). lanjoki, Porvoonjoki and Pernajanjoki. Thus both in the open and coastal Gulf According to current data a large part of Finland (DIP up to 100 mg P m-3), high of the inner and middle Archipelago winter concentrations lead to intensive Sea showed increased phosphate con- vernal primary production and subse-

centrations (3 to 5 mg P m -3). In the whole quent sedimentation of dead algae. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 45

Fig. 5.5. Mean surface values for inorganic nitrogen in summers 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

46 ○○○○○○○○○○○○○ The Finnish Environment 472

Fig. 5.6. Mean surface values for inorganic phosphorus in summers 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 47

Fig. 5.7. Mean bottom layer values for inorganic phosphorus in summers 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

48 ○○○○○○○○○○○○○ The Finnish Environment 472 Furthermore the P values are elevated 5.1.3 Inorganic N/P ratio by internal loading, which is also partly caused by the high sedimentation of The wintertime distribution of DIN: organic matter. DIP indicates a clear P-controlled spring In the coastal waters, highest deep production in the Bothnian Bay and water values of both N and P were re- generally in river estuaries, due to the corded in certain semi-enclosed basins high N:P ratio of river water (e.g. Ala- and estuaries in the coastal Gulf of Fin- saarela 1980, Pitkänen 1994) and also land and in the Archipelago Sea. Typi- to effective P precipitation in the Both- cal for the distribution in some coastal nian Bay (Voipio 1969). In the Bothni- areas, excluding the Bothnian Bay, was an Bay and in the easternmost Finnish that in contrast to surface values, the waters of the Gulf of Finland the ratio near-bottom concentrations increased indicated co-limitation of N and P, from the coastline towards the outer whereas in the western Gulf of Finland coastal waters, where the main sedi- and in the outer Archipelago Sea N mentary basins are located. appeared to be the primary controlling factor of the spring bloom. During the Bioavailable nutrients and 1990s the conditions have changed es- the N:P ratio pecially in the middle and western Gulf of Finland, where the controlling The estimation of nutrient loading is most role of N became stronger, probably often based on the fluxes of total amounts of nutrients. In the receiving waters, algae due to the intensified internal loading and other primary producers readily use which has a low N:P ratio. In the Ar- only a part of the nutrients, whereas some chipelago Sea the role of N as the pri- nutrient forms may become available slowly mary controlling factor has also in- or may be entirely inert. Generally, nutri- creased (cf. Kirkkala et al. 1998). ents in dissolved form are more readily available than those in particulate form. The situation is largely the same Thus to efficiently abate eutrophication, according to the late summer data (Fig. the load reduction measures should be 5.8). However, on the basis of inorganic targeted towards bioavailable nutrients concentrations the middle Gulf of Fin- rather than total nutrients. land also seemed to be co-limited and Calculating the ratio of inorganic (totally the estuarine and archipelagic areas of bioavailable) N and P concentrations (NH + 4 potential P limitation were smaller NO3+NO2-N / PO4-P) helps us to make (usually approximate) conclusions on the potential compared with conditions before the controlling roles of these two nutrients in the spring bloom. Good correspondence can eutrophication process. According to Fors- be found between the present results and berg et al. (1978), nitrogen is the main lim- the experimental results on nutrient limiting factor when the ratio is below 5, whereas phosphorus limits primary pro- itation obtained by Tamminen (1990), duction when the ratio is higher than 12. Kivi et al. (1993), Pitkänen and Tam- According to Ryther and Dunstan (1971) minen (1995) and Tamminen and Kivi nitrogen limitation is more likely when the (1996). During the later half of the 1990s ratio is below 10 and phosphorus limita- summer concentrations around 10 mg tion when the ratio is higher than 10. It m-3 of free DIP were measured from the must be remembered that judgements based on nutrient concentration ratios are mixed surface layer in the middle and based on momentaneous concentrations western Gulf, indicating clear N con- and can thus produce only very tentative trol of primary production. This extra conclusions in cases when both DIN and pool of DIP disappeared in the sum- DIP are low. In cases where clearly meas- mer of 1999, when the formation of urable values of either DIN or DIP are continuously present during the growth pe- blue-green algal blooms was also less riod the judgement is easy and reliable. prominent than during the warm sum- In cases where elevated values of both nu- mer of 1997. trients are present (usually in inner river estuaries) some other factor, e.g. light

availability, controls primary production. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 49

Fig. 5.8. Mean ratio of inorganic N/P in surface layer in summers 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

50 ○○○○○○○○○○○○○ The Finnish Environment 472 5.2 Trends since the late et al. 1997b, Kirkkala 1998). However, increasing nutrient trends can be dis- 1980s cerned only for phosphate- and total 5.2.1 The Gulf of Finland P, while DIN decreased (Figs. 5.13a, b,c,d). In the 1970s and the 1980s, in- A typical behaviour for the concentra- creasing trends for both P and N con- tions of N in the Gulf of Finland in the centrations were evident (Pitkänen et 1970s and the 1980s was an average al. 1987, Kirkkala 1998) and could at increase regarding both winter and least partly be explained by intensified summer data (Figs. 5.9a,b; 5.10a,b; agriculture and fish-farming. Howev- 5.11a,b; 5.12a,b). This was evident in er, in coastal areas off larger towns P the open sea values, which approxi- concentrations showed decreasing mately doubled in the surface layer of trends, due to the introduction of P the Gulf during the 1970s and the 1980s precipitation at the municipal treat- (Perttilä et al. 1996). In the coastal wa- ment plants. ters the development was very similar, In the middle Archipelago Sea, a although the trend was less steep in the drastic increase of phosphate-P from 10 eastern Gulf. As the concentrations of to 30 mg P m-3 in the summertime near- P in the surface layer did not marked- bottom concentrations took place dur- ly change, and showed even some un- ing the late 1980s and the 1990s. At the certain decrease in the eastern Gulf at same time the deep water oxygen con- the same time, the inorganic N:P-ratio centrations continuously decreased gradually increased. and reached 6–7 mg l-1 (ca. 50% satura- During the 1990s the development tion, Fig. 5.13d) in 1997. These phenom- was the opposite: N concentrations ena indicate increased sedimentation slowly started to decrease, while P con- of organic detritus caused by increased centrations started to increase due to primary production and /or possible the intensified internal loading. The anoxia and internal loading at the sed- decreasing trends of N in both the open iment-water interface. Simultaneously, sea (Perttilä et al. 1996) and in coastal an increase of P was also evident in the waters in the 1990s were most proba- summertime surface concentrations. bly connected with the decrease of N The middle Archipelago Sea is loading by over 30% to the Gulf of Fin- mainly limited by nitrogen during the land during the decade, while the in- mid- and late summer months, al- crease of P, despite the decreased ex- though the situation can oscillate be- ternal loading (see section 3), was due tween control by nitrogen and phos- to the strong increase of internal P load- phorus (Tamminen et al. 1996). The ing in the mid 1990s (Figs. 5.9a,b; generally increased DIP and decreased 5.10a,b, Pitkänen and Välipakka 1997). DIN according to the wintertime data Thus the nutrient limitation clearly indicate that the development further shifted more pronouncedly towards N strengthened towards the end of the control during the 1990s (cf. Kivi et al. 1990s. The results of Kirkkala et al. (1998) 1993, Tamminen et al. 1996). The most based on total nutrients from the mid- striking sign of this was the increase of dle and southern Archipelago Sea also unfixed DIP in the outer coastal wa- support reasons to similar conclusions. ters in July-August 1997–98 (Figs. A possible factor in the observed 5.11a,b; 5.12a,b), causing strong blooms development is the increased flow of of Nodularia spumigena in the warm P from the Gulf of Finland (cf. Helmin- summer of 1997. en et al. 1998), where P concentrations strongly increased in the late 1990s (Fig. 5.2.2 The Archipelago Sea 5.10a). Factors affecting in the same direction are the possibly increased In the 1990s, eutrophication proceed- benthic outflux of P and/or increased

ed in the Archipelago Sea (Bonsdorff sedimentation of organic matter. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 51 Fig. 5.9a. Surface values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Huovari in the eastern Gulf of Finland in winter 1979–1998. See Fig. 1.1 for the location of the station.

Fig. 5.9b. Bottom values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Huovari in the eastern Gulf of Finland in winter

1979–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

52 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 5.10a. Surface and bottom values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Länsi-Tonttu off the coast of Helsinki in winter 1979–1998. See Fig. 1.1 for the location of the station.

Fig. 5.10b. Bottom values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Länsi- Tonttu off the coast of Hel-

sinki in winter 1979–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 53 Fig. 5.11a. Surface values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Huovari in the eastern Gulf of Finland in summers 1979–1998.

Fig. 5.11b. Bottom values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Huovari in the eastern Gulf of Finland in summers

1979–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

54 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 5.12a. Surface values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Länsi- Tonttu off the coast of Helsinki in summers 1979–1998.

Fig. 5.12b. Bottom values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Länsi- Tonttu off the coast of Helsinki in summers

1979–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 55 Fig. 5.13a. Surface values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Seili in the Archipelago Sea in winter1979–1998. See Fig. 1.1 for the location of the station.

Fig. 5.13b. Bottom values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Seili in the Archipelago Sea in

winter 1979–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

56 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 5.13c. Surface values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Seili in the Archipelago Sea in summer 1979–1998.

Fig. 5.13d. Bottom values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Seili in the Archipelago Sea in

summer 1979–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 57 5.2.3 The Bothnian Sea and In the NE Bothnian Bay, the clear the Bothnian Bay decreases in both N and P concentrations since the late 1980s (Figs. 5.15b,c) In general, less clear changes can be were most probably attributed to the found in the rest of the Gulf of Bothnia improvements in sewage treatment compared with the Archipelago Sea. A techniques and to smaller river runoff decreasing trend in the wintertime DIN in the 1990s (indicated locally also by appears possible during the 1990s in the decreased salinities). The trend was the coastal waters of both sea areas more pronounced for P than for N. The (Figs. 5.14, 5.15a). The open Gulf val- decrease of total P by 4 to 5 mg m-3 dur- ues also support similar conclusion ing this period is in accordance with when the present data is compared to the reduction of the load of P from lo- that of the early 1980s (Pitkänen et al. cal point sources by about 50% (see 1987). The trend may be connected chapter 3). with the decrease in the river loads of N in the 1990s mainly due to the decreased runoff (see chapter 3). There may also have been changes in the limitation balance between N and P, due to the increased P concentrations in the open Bothnian Sea, possibly caused by the decreased vertical stability (cf. Sanden et al. 1996).

Fig. 5.14. Surface values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Bergö in the Northern Bothnian Sea in winter 1979–1998. See Fig. 1.1 for the location

of the station. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

58 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 5.15a. Surface values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Hailuoto in the northern Bothnian Bay in winter 1979–1998. See Fig. 1.1 for the location of the station.

Fig. 5.15b. Surface values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Hailuoto in the northern Bothnian Bay in

summer1979–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 59 Fig. 5.15c. Bottom values for total N, inorganic N (DIN), total P, inorganic P (DIP), salinity and oxygen at Hailuoto in the northern Bothnian Bay in winter

1979–1998. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

60 ○○○○○○○○○○○○○ The Finnish Environment 472

Changes in phytoplankton

○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 6

Pirkko Kauppila and Liisa Lepistö

6.1 Areal distribution of bays off Helsinki, the concentrations of chlorophyll a decreased in the late phytoplankton chlorophyll a 1980s. This was a result of starting to lead purified waste waters to the out- A typical feature of summertime con- er archipelago. As a consequence, the centrations of phytoplankton chloro- strongly eutrophied area (10 to 15 mg phyll a, commonly used as a measure- chl a m-3) in the bays decreased in ex- ment of eutrophication, is an increase tent (Pesonen et al. 1995). At the same from the open sea towards the coast time, a decrease in the concentrations and from the northern Bothnian Bay of P resulted in an increase in the inor- towards the eastern Gulf of Finland ganic N:P ratio, which favoured the

(e.g. Pitkänen et al. 1987, Kauppila et non-N2-fixing blue-green algae (Peso- al. 1995, HELCOM 1996, Fig 6.1). In the nen et al. 1995, Räisänen & Viljamaa open Gulf of Finland, the slightly eu- 1998). Simultaneously with the clear trophic area (3 to 5 mg chl a m-3) from decrease of nutrient loading, the blue- the Kotka archipelago westwards cov- green alga Planktothrix agardhii, which ered the whole open Gulf in the 1990s, is considered to indicate eutrophica- whereas in the 1980s the level of chlo- tion in brackish waters (Niemi 1973, rophyll a at the entrance to the Gulf was Hällfors et al. 1981), lost its dominance still below 3 mg m-3 (Pitkänen et al. in the inner bays. 1987). This was in accordance with the In the outer Archipelago Sea, the increasing trend of chlorophyll a iden- level of chlorophyll a (below 3 mg m-3) tified in the western Gulf in the 1980s equalled the level observed in the open (Grönlund and Leppänen 1990). The sea. In the middle Archipelago Sea, the westward movement of the border of border of the slightly eutrophied area the slightly eutrophied area during the (3 to 5 mg chl a m -3) moved 20 km west- 1980s can be explained by the weaken- wards to the outer archipelago during ing of vertical stability and by an in- the 1980s, coinciding with the increase crease in N concentrations (Perttilä et in the level of P (see also Kirkkala 1998). al. 1996). The increased trophic status Increased trophic status in the 1980s in the eastern Finnish archipelago was has partly been explained by intensi- mainly due to the deep water or sedi- fied fish farming and by possibly in- ment nutrient reserves, which because tensified upwellings. On the other of rather unstable physical stratifica- hand, anoxia in semi-enclosed basins tion, could reach the productive layer in the late 1990s may be a consequence during mixing events and storms of internal loading (cf. Pitkänen and (Pitkänen 1991, Pitkänen et al. 1993). Välipakka 1997) and net fluxes of nu- In the coastal waters of the Gulf trients from the western Gulf of Fin- of Finland, strongly affected by nutri- land (Helminen et al. 1998). ent inputs from local sources, the eu- In the open Gulf of Bothnia, the lev- trophied area (5 to 10 mg chl a m-3) in el of chlorophyll a was below 3 mg m-3. the 1990s extended as far as 5 to 15 km In the coastal waters, the eutrophied

from the coast. However, in the inner area was limited to the archipelago off ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 61

Fig. 6.1. Mean surface values of chlorophyll a in summers 1991–1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

62 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 6.2. Concentrations of chlorophyll a at the stations of a) Huovari, b) Haapasaari c) Ängsön d) Länsi-Tonttu, e) Seili and f) Truutinpauha in late summers 1979– 2000. See Fig. 1.1 for the location of the station.

Fig. 6.3. Concentrations of chlorophyll a at the stations of a) Reposaari, b) Bergö, c) Storbådan, d) Repskär, e) Hailuoto and f) Pohjan- tähti in late summers

1979–2000. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 63 Uusikaupunki, the river Kokemäenjoki of phytoplankton in mid June, blue- estuary, the Quark archipelago, the ar- green algae start to increase and even- chipelagos off Kokkola and Pietarsaari tually dominate the phytoplankton and the NE Bothnian Bay from Raahe communities in the eastern Gulf of Fin- to Tornio. In the Kokemäenjoki estuary land and they are abundant in the Ar- and in the archipelagos off Kokkola, chipelago Sea and occasionally in the Pietarsaari and Oulu the border of the Gulf of Bothnia. The blue-green algal slightly eutrophied area moved west- community is generally dominated by

wards during the 1980s and 1990s de- N2-fixing Nostocales. spite reduction in the anthropogenic In mid May 1998, at Huovari in the loads of nutrients. The change in the eastern Gulf of Finland phytoplankton trophic status may thus be related to biomass was as high as 16.9 g m-3. Dia- the general eutrophication of the open toms dominated the phytoplankton com- sea. The increasing trends of P in the munity. The most abundant species was open Bothnian Sea and that of N in the small sized Achnanthes taeniata, com- whole open Gulf have been explained prising 67% of the total biomass. The by weakening of vertical stability, re- second main group was dinoflagel- sulting from decrease in salinity in the lates, mainly Scrippsiella hangoei with deep water (Sanden et al. 1996). 32% of the biomass. However, by June Consequently, the higher trophic the dinoflagellate Peridiniella catena was status was clear especially in the Gulf a dominating species. In July, blue- of Finland and in the Archipelago Sea green algae succeeded the diatoms. during the 1980s. However, this trend From the beginning of July to late Au-

levelled out in both areas in the mid gust the N2-fixing Nostocales such as 1990s (Fig. 6.2). However, in the east- Nodularia sp. and Aphanizomenon sp., ern Gulf of Finland and in the middle dominated the biomass and the bio- Archipelago Sea the concentrations of mass portion of Aphanizomenon sp. was Chl started to increase again in the late ca. 40%. In September the proportion of

1990s. In the Gulf of Bothnia, Chl has the non-N2-fixing blue-green algae, such usually been below 3 mg m-3 (Fig. 6.3). as Snowella lacustris (Chroococcales) and Planktothrix agardhii (Oscillatoriales), increased approximately to 30% of the 6.2 Seasonal variations of total biomass and Nostocales decreased to ca. 10%. phytoplankton At Längden in the western Gulf of Finland the spring maximum bio- The spring bloom maximum of phyto- mass value was 28.0 g m-3, observed at plankton in the northern Baltic Sea re- the end of April. This maximum was veals a normal brackish-water commu- produced solely by the dinoflagellate nity, dominated by diatoms (Achnanthes Scrippsiella hangoei (97%). In mid May, taeniata, Diatoma tenuis) and dinoflag- dinoflagellates were succeeded by di- ellates (Peridiniella catenata, Scrippsiella atoms. Skeletonema costatum, Chaetoceras hangoei, Glenodinium spp., Fig 6.4). The spp. and Achnanthes taeniata dominat- peak time and the species composition ed. Summer phytoplankton was dom- of the spring bloom may vary from inated by the dinoflagellate Heterocapsa year to year. The peak of the spring bi- triquetra but blue-green algae were omass is not always detected during scarce during the summer. routine monitoring programme sam- In the Archipelago Sea the spring pling. Furthermore, development of maximum biomass value of 7.9 g m-3 the spring bloom occurs later in the was produced by diatoms (95 %), such north. In Hailuoto, the spring bloom as Chaetoceras wighami and Achnanthes develops in late May, whereas at taeniata in mid April 1998. By the mid Längden in SW Finland peak normal- May the total biomass was decreased to

ly occurs in late April. After a decline 3.4 g m-3 and dominated by dinoflagel- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

64 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 6.4. Seasonal variation of phytoplankton biomasses in the eastern Gulf of Finland (at Huovari), the western Gulf of Finland (at Längden), the Archipelago Sea (at Seili), the northern Bothnian Sea (at Bergö) and the northern Bothnian Bay (at Hailuoto) in 1998.

lates (58%), such as Peri-diniella catena. from 0.1 g m-3 in June to 0.5 g m-3 in July

In August blue-green algae, mainly N2- 1998. The diatoms Achnanthes taeniata fixing Aphanizomenon sp., increased to and Chaetoceras spp. dominated in May 52% of the total biomass. Still in Sep- and Thalassiosira baltica in July. Crypto- tember this taxa contributed 30% of the monads and Chrysomonads were abun- total phytoplankton biomass. dant in July. In August-September N2-fix- In the Gulf of Bothnia no clear ing blue-green algae increased, mainly spring maximum was observed. Phy- Nodularia sp. and Aphanizomenon sp.

toplankton biomass was low varying ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 65 In the northernmost part of the Baltic Sea, in Hailuoto, phytoplankton 1.5 Längden started to increase in early June. The mg l -1 -3 maximum total biomass, 2.4 g m , ob- 1 served in early June, was formed by diatoms (97%), mainly Diatoma tenuis. This species dominated the phyto- 0.5 plankton community still in mid July. Cryptomonads and Chrysomonads 0 became abundant at the end of the 1993 1994 1995 1996 1997 1998 summer. Others Chlorophy ta Diatoms 6.3 Long term changes Heterokont.flags Crypto- anddinophyta in phytoplankton Cyanophyta

Changes in the phytoplankton total bi- Fig. 6.6. Late summer phytoplankton spe- omasses and species composition are cies composition and biomasses at Längden affected by several factors, revealing in the western Gulf of Finland in 1993– variations both in nutrient concentra- 1998. tions and hydrographical conditions. Nutrient concentrations are affected both by external loading (e.g. from river water) and internal loading (e.g. from sediment). Hydrodynamics in- the Archipelago Sea during the 1980s clude, e.g. mixing conditions in water, and 1990s can be seen as an increase in which affect not only nutrient concen- phytoplankton total biomasses in late trations but also the possibility for phy- summers (Figs. 6.2, 6.5–6.7). In the east- toplankton to persist and grow in the ern Gulf of Finland, the considerable productive surface layer. increase in phytoplankton biomasses in Eutrophication in the outer archi- the late 1980s coincided with the gen- pelago of the Gulf of Finland and in eral increase in nutrient concentrations. The phytoplankton biomasses were generally high during the 1990s, excluding a decrease in the middle of the decade (Fig. 6.5). Blue-green algae clearly dominated phytoplankton in 1991, 1993 and 1998. The release of phosphorus from sediment during the extensive oxygen deficit in the late 1990s was observed as elevated phytoplankton total biomasses and high chlorophyll a values (Figs. 6.2, 6.5). Strong surface accumulations of blue- green algae were recorded throughout the whole archipelago area in 1996 and 1997 (Pitkänen and Välipakka 1997, Kauppila and Lepistö 1997, 1998). In the outer archipelago off Hel- sinki, phytoplankton total biomasses Fig. 6.5. Late summer phytoplankton species composition and biomass- did not appear to increase despite of

es at Huovari in the eastern Gulf of Finland in 1979-1999. the increase in nutrient concentrations ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

66 ○○○○○○○○○○○○○ The Finnish Environment 472 in the area. This is due to the fact that waste waters have been conducted to 1.5 the outer archipelago since the late Seili mg l-1 1980s (Pesonen et al. 1995). In fact, in the innermost bays biomasses clearly 1 decreased after the closing of sewage treatment plants. In the western Gulf of Finland, phytoplankton total bio- 0.5 mass had an increasing trend in the 1990s (Fig. 6.6). Only in 1994 was the 0 average biomass exceptionally low. 1991 1992 1993 1994 1995 1996 1997 1998 Blue-green algae were abundant in Cyanophyta Diatoms 1993 and 1997, when dense surface ac- Crypto- anddinophyta Chlorophyta cumulations also occurred. In general Heterokont.flags Others dinoflagellates dominated. In the outer Archipelago Sea, total phytoplankton biomasses have slightly increased since the mid 1990s Fig. 6.7. Late summer phytoplankton species composition and biomass- (Fig. 6.2, 6.7). The increase of phyto- es at Seili in the middle Archipelago Sea in 1991–1998. plankton biomasses in the innermost archipelago in the 1980s and 1990s was in accordance with the trend of phosphorus level, which started to increase coincided with the large outflow of N- since the middle 1980s (Hänninen et al. rich and oligohaline water of the River 1997). Blue-green algae occurred abun- Neva in 1991 and 1993 (Kauppila et al. dantly in 1997 and 1998. 1995). This episode occurred during a Changes in environmental condi- period of southwesterly winds at a tions in the Gulf of Finland and in the time when the mixed surface layer was Archipelago Sea were reflected not thin. The dominance of P. agardhii in only as an increase in total biomasses the late summer of 1995 after rather but also in changes in the phytoplank- similar summer conditions can also ton species composition and in the re- imply the possible effect of River Neva lationships of the dominating phyto- waters, because in September the sa- plankton taxa. In the eastern Gulf of linity was as low as 3.3–3.5 psu and Finland cryptophytes and dinoflagel- strong SW winds (8.3 m s-1) were pre- lates, mainly Dinophysis acuminata, vailed. In the summer of 1998 the bio- dominated the late summer plankton mass of blue-green algae was also high, community in the 1980s (Fig. 6.5). The with the dominance of Aphanizomenon dominance of these plankton taxa was sp., but the hydrographical conditions succeeded by blue-green algae, main- did not differ from normal, e.g. the sa- ly Aphanizomenon sp. and Planktothrix linity was as high as 3.9–4.8 psu. agardhii. Those two taxa contributed In the central Gulf of Finland, most to phytoplankton total biomass- changes in species composition oc- es in the late 1980s and 1990s. The nu- curred mainly in the group of blue- trient ratios and hydrodynamic condi- green algae. The increase in the inor- tions determined which one of the two ganic N:P ratio was caused by waste blue-green algae achieved dominance. waters originating from the Helsinki- The nearly optimal inorganic N/P ra- Espoo area. This favoured flourishing tio for phytoplankton growth in the late of the blue-green algal order Chroococ- cales at the expense of A. flos-aquae, 1980s probably favoured more the N2- fixing (heterocystic) Aphanizomenon which is capable of nitrogen fixation (Pesonen et al. 1995, Räisänen & Vil- than the non-N2-fixing P. agardhii. On

contrary, the dominance of P. agardhii jamaa 1998). Similar changes in nutri- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 67 ent ratios and species composition also their gas vacuoles. Furthermore, blue- occurred in the inner bays after clos- green algae are the only toxic phyto- ing of the wastewater treatment plants plankton group in the Baltic, which in Helsinki. forms extensive surface accumulations. In the outer Archipelago Sea, dom- In the northern Baltic Sea, surface inant phytoplankton species in the sum- accumulations of blue-green algae in mers of the early 1990s consisted mainly late summer occur most abundantly in of diatoms (Coscinodiscus granii), crypto- the Gulf of Finland and in the Archi- monads (Plagioselmis prolonga, Teleaulax pelago Sea. In the Gulf of Finland, the spp.) and dinoflagellates (Dinophysis accumulations usually consist of the acuminata, Katodinium rotundatum, Fig. blue-green algae Aphanizomenon sp., 6.7). Additionally, blue- green algae (e.g. Nodularia spumigena and Anabaena Anabaena lemmermannii) and green al- lemmermannii. In the western Gulf, dis- gae (e.g. Pyramimonas virginica) were appearance of the accumulations in the also common. The high phytoplankton late 1980s was associated with the in- biomass in 1993 was mainly produced creased N/P ratio and the subsequent by the large diatom C. granii. The dom- loss of competitive advantage provid- inance of blue-green algae in the ed by nitrogen fixation (Kononen late1990s obviously indicates the effect 1992). Although abundant in the wa- of eutrophication on the phytoplank- ter column, P. agardhii does not often ton community. The accumulations of form surface accumulations (Lindholm blue-green algae also seemed to be- 1992). In the early 1990s the reappear- come stronger in the 1990s (Kirkkala ance of accumulations of blue-green 1998). One explanation for the domi- algae in the western Gulf was ex- nance of blue-green algae as a response plained by increased phosphorus con- to increased P levels in the outer Ar- centration in the near bottom layers chipelago Sea may be anoxia. during the latest stagnation period in 1977–1992 (Nehring and Matthäus 1991, Kahru et al. 1994). 6.4 Nuisance algal The accumulations of blue-green algae in the Gulf of Finland are often blooms enhanced by upwellings of near-bottom waters carrying phosphorus Surface accumulations of filamentous abundantly up to the productive sur- blue-green algae in late summers are a face layer. Exceptional hydrographical regular phenomenon in the Baltic Sea conditions can also favour transporta- (e.g. Kahru et al. 1994). The first records tion of blue-green algae near to coast, of such events date back to the mid 19th such as in October 1987 when Microcystis century (Pouchet and de Guerne 1885). aeruginosa formed a massive bloom in However, in recent years the extent and the south-eastern Finnish archipelago intensity of the accumulations have (Niemi 1988, Pitkänen et al. 1990). In been an increasing environmental con- summer 1997, the accumulations in the cern because of anthropogenic eu- whole Gulf of Finland were most ex- trophication. The dominance of certain tensive and prolonged ever recorded blue-green algae in phytoplankton (Rantajärvi 1998). The level of P con- communities in late summers is based centration was elevated in the produc- on their ability to fix dissolved molec- tive surface layer due to the release of

ular N2 and to use phosphorus stored P from sediment during extensive ox- in their cells in the period when the ygen deficit in summer 1996 (Pitkänen growth of other algae is usually limited and Välipakka 1997). The calm and by nutrients. During calm and warm warm weather conditions in summer weathers blue-green algae tend to form 1997 also favoured the accumulation

surface accumulations with the aid of of blue-green algae. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

68 ○○○○○○○○○○○○○ The Finnish Environment 472 In the Archipelago Sea, surface accumulations of blue-green algae, mainly formed by the nitrogen-fixing species Aphanizomenon spp., Nodularia spumigena and Anabaena sp., are most common in July and August (Häkkilä 1998). The accumulations usually occur most abundantly in the outer archipelago and open sea, partly due to the lower ratio of inorganic N/P, which favours heterocystic blue-green algal species (Fig. 6.8). The occurence of cyanobacterial accumulations in the outer Archipelago Sea is also affected by the directions of prevailing winds. In summers 1998–2000, accumulations were also recorded in the inner Archi- pelago Sea (Häkkilä, pers. com), which Fig.6.8. Harmful algal blooms registered in is mainly due to the increase of N lim- the Archipelago Sea in the 1990s. itation in the whole sea area (cf. Kirkka- la et al. 2000). The excess P in the innermost coastal areas is most probably derived from internal loading. In the Gulf of Bothnia, surface accumulations of blue-green algae are taste of fish and poisonous phyto- usually restricted by the low concen- plankton stocks. The toxic flagellate tration of inorganic phosphorus and Prymnisium parvum caused fish kills in generally lower water temperatures June 1990 in Dragsfjärd, SW Finland than in the more southern areas of the (Lindholm and Virtanen 1992). The Baltic Sea. However, in most recent mass mortality of birds in the eastern years accumulations of blue green al- Gulf of Finland in spring 1992 was gae Anabaena spp. have been recorded probably caused by toxic diatoms in some inner coastal areas (Kauppila (Kauppi 1993). & Lepistö 1998). Surface accumulation of blue- green algae in exceptional seasons seem to have intensified in the 1980s and 1990s. This can be considered as a sign of eutrophication. As mentionend earlier a fresh water species Microcystis aeruginosa formed a massive bloom in the eastern Gulf of Finland in October 1987 (Niemi 1998, Pitkänen et al. 1990). In January 1998 accumulations of Aph- anizomenon sp. were observed in the south-eastern coast of the Archipelago Sea which was ice free during a prolonged period of calm and mild weather in January. Algal nuisances have taken the form of e.g. liming of bottom layers and fishing nets, dirty beaches, spoiled Microscopic view of blue-green alga Nodularia spumigena.

Photo P. Kokkonen ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 69 Blue-green algae and N2-fixation Phytoplankton communities Blue-green algae have bacteria-like struc- and biomass ture and they have been classified as cy- Dinoflagellates are a very diverse group anobacteria. However, they differ from and very important members of phyto- bacteria as they function like plants (au- plankton assemblages in marine and totrophs with oxygen production). Several brackish waters. The more or less oval species in Order Nostocales are able to fix medium-sized (ca. 30 µm) flagellated nitrogen. Scripsiella hangoei is often the dominating Some of blue-green algae, e.g. the gen- dinoflagellate species in vernal mass oc- era Anabaena, Aphanizomenon and Nodularia currences, together with diatoms such as in the order Nostocales have heterocysts Achnanthes taeniata. Scripsiella hangoei is a which are quite large in size and they do typical cold-water form, and is favoured not contain chlorophyll. Heterocysts are by high nutrient concentrations in spring,

specialized for aerobic N2-fixation (N2- i.e. it is an indicator of eutrophication. Si- gas fixation directly into organic N). The multaneously with the decrease in nutri- blue-greens that are able to fix nitrogen ents, the plankton community starts to may be abundant when there is a high change and Scripsiella cysts are formed concentration of phosphorus in water and and they sink to the bottom. nitrogen concetration is low. Anabaena and Diatoms are the other important phy- Aphanizomenon are very common in fresh toplankton group in brackish waters. The waters. Especially the genus Anabaena in- moderately small sized (ca. 5 x 25 µm) cludes toxic strains. Aphanizomenon is diatom Achnanthes taeniata is a cold wa- abundant in late summer and still in winter diatom and thus very common dur- ter and is never observed to be toxic in ing spring. Due to the intensive cell divi- brackish waters. However, mass occur- sion cells are often small, only 4 x 10 µm rences of Nodularia, living in brackish which prevents them in the productive waters, are always toxic. layer.

Non N2-fixing blue-green algae are those In brackish waters, the vernal phyto- without any special cell forms, i.e. all cells plankton biomasses are generally higher are uniform. For example Planktothrix than biomasses in late summer. Howev- agardhii (Order Oscillatoriales) is very abun- er, phytoplankton total biomass and its dant in eutrophic brackish waters with seasonal variation reflects nutrient con- high concentrations of nitrogen. This spe- centrations, mainly phosphorus, in the en- cies can typically exist in deep waters as vironment. In oligotrophic waters, phy- it is able to survive in conditions of low toplankton biomass values are low even light. The genus Microcystis (Order Chroo- during spring. The variation of total phy- coccales) is occasionally observed as mass toplankton biomass is low, from 0.4 g m-3 occurrences in the Baltic Sea, although it to 0.6 g m-3 in late summer. In mesotroph- is typical for highly eutrophic fresh wa- ic waters, the variation is still moderately ters. low, from ca. 0.5 g m-3 in spring to 1.0 g m-3 in late summer. In eutrophic nutrient-rich waters, the spring maximum is a drastic event and biomass may increase to ca. 30 g m-3 in April to May, which is thirty times higher than the average summer biomass. On average vernal biomass is ca. 7.3 g m-3. Summer phytoplankton assemblages are dominated by blue-green algae, the aver-

age total biomass being ca. 1 g m-3 . ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

70 ○○○○○○○○○○○○○ The Finnish Environment 472

Changes in phytobenthos

○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 7

Saara Bäck, Annamaija Lehvo, Jouko Rissanen and Pentti Kangas

Coastal ecosystem diversity is richest on the struction. Eutrophication is related ei- border of land and sea. The mosaics of ther to local point sources or to long- the islands and skerries are the most distance pollution sources. When eu- typical feature of the Finnish coastline. trophication increases, sedimentation The phytobenthic zone is defined here and species favouring eutrophication as the plant and animal communities occupy a larger area. Physical habitat of the photic zone. It offers enormous- destruction includes losses of habitats ly different kinds of habitats support- by e.g. building activities. The factors ing different types of vegetation with threatening the phytobenthos in the associated fauna. The distribution of Baltic Sea are likely to become more plants on the sea bed depends on sev- severe, in many areas, in the future. eral environmental factors. The verti- Some of these phytobentic changes cal distribution is governed by light have been so drastic that great concern conditions, and the horizontal distri- and awareness of the phytobenthos bution is influenced mainly by salinity. zone has developed. Long-term stud- Rocky bottoms are often dominat- ies on littoral changes in the Baltic Sea ed by macroalgae. A typical zonation are rare. The following information of macroalgae is usually found on ex- was gathered from various reports and posed rocky shores. Filamentous algae scientific articles. dominate close to the water level, brown algae (Fucus vesiculosus) in the shallow sublittoral, and red algae at the 7.1 Species composition greatest depths. Sandy bottoms are rare along most of the Finnish and Swed- of macroalgae ish coasts, where rocky bottoms and softer sediments are the prevailing bot- Studies in coastal areas from all over tom types (Rantataro 1992). Sandy and the Baltic Sea region have shown neg- muddy bottoms are characterised by ative changes in the macroalgal vege- phanerogams. The bottom vegetation tation. Along the Finnish coast, chang- in shallow bays may also be dominat- es such as decreased occurrence of pered by charophyte meadows. Small, ennial red and brown algae (Haahtela shallow and sheltered flads and gloes and Lehto 1982, Kangas et al. 1982), are clearly delimited water bodies, ei- increased occurrence of fast-growing ther still connected with the sea or cut filamentous algae (Mäkinen et al.1994) off from the sea by land uplift. and drifting algal mats causing anoxia The main threats to phytobenthos has occurred (Norkko and Bonsdorff are considered to be increasing eu- 1996). Furthermore, the upward move-

trophication and physical habitat de- ment of the algal belts due to increased ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 71 sedimentation, overgrowth by epi- creased primary production. In 1991 F. phytic algae and increased shading by vesiculosus was still lacking but the plankton have been widely document- amount of filamentous algae had de- ed (Mäkinen et al. 1984). creased. In the inner and middle archi- In the outer archipelago of the pelago F. vesiculosus was replaced by fil- eastern Gulf of Finland, the upper filamentous brown and red algae (Mäk- amentous algal zone is dominated by inen et al. 1994). F. vesiculosus produc- Cladophora glomerata, the intermediate es gametes in May and June (Bäck zone by Fucus vesiculosus (1–5 m depth) 1993) when sediment cover is high, and and the deep water filamentous algal P. littoralis in October-December (Ki- zone by Cladophora rupestris (Bäck et al. irikki and Lehvo 1997) when the sedi- 1993b, Valovirta & Porkka 1996). How- ment cover is minimal. It seems possi- ever, according to Valovirta & Porkka ble that increase in summertime sedi- (1996) the filamentous algal zone has ment cover could cause changes in the become sparse or has disappeared al- composition of the macroalgal vegeta- together even at semi-exposed sites. tion by favouring species which release They have found that in semi-exposed their spores in autumn and winter, localities the Hildenbrandia zone can when storms clean the rock surfaces of start immediately below the Fucus zone loose sediment (Kiirikki & Lehvo 1997). at a depth of about 4 metres. They also In the Åland archipelago, chang- suggested that a thick cover of the polyp es in the littoral zone follow those of Cordylophora caspia is a sign of eutro- the Gulf of Finland and the Archipela- phication. go Sea. In the Lågskär area of the Åland In the South coast of Finland, Sea, Rönnberg and Mathiesen (1997) Kukk & Viitasalo (1997) reported that studied macroalgal vegetation in the the previously extensive Enteromorpha 1990s and compared the results to those spp. belt in the inner archipelago off the of the 1950s, when a total of 26 species city of Helsinki decreased and gave were identified. The most diverse vege- way to a Cladophora glomerata belt dur- tation, 18 species, was recorded at a ing the period 1978–1995, after loading depth of 4–7 m. Comparisons with the with local wastewater was finished in results from 1956 indicated that the total 1978. Phanerogams and filamentous number of macroalgal species had de- brown algae appeared Fucus did not creased by six. Species showing a strong become established even if suitable decrease included Sphacelaria arctica, rock surfaces were present. The chang- Cladophora rupestris, Stictyosiphon tortilis es reflect the advances in wastewater and Polysiphonia fucoides. Species exhib- treatment of the city of Helsinki. The iting a clear increase were the filamen- recovery of the phytobenthos is also tous Pilayella littoralis and Ectocarpus due to resiting of the discharge points siliculosus, Fucus vesiculosus and the red of the adjacent urban areas away from alga Rhodomela confervoides. innermost bays to the open fringe of the archipelago waters. Along the SW coast of Finland in- 7.2 Fucus vesiculosus vestigators have recorded a shift from Fucus vesiculosus -dominated bottoms recovery towards dominance of the filamentous Pilayella littoralis. In some places Fucus vesiculosus is the only large per- F. vesiculosus has been replaced by ennial seaweed which is widespread phanerogams, mainly by Potamogeton in the brackish Baltic Sea, and as such spp. and Zannichellia palustris. The bot- it forms the habitat for e.g. the hard- tom quality change was explained by bottom macrofauna. Fucus vesiculosus

heavy sedimentation due to e.g. in- is widely distributed throughout the ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

72 ○○○○○○○○○○○○○ The Finnish Environment 472 Finnish coast (Björkquist and Bergsröm a depth of 0.5–2 m in sheltered and at 1997, Bäck and Ruuskanen 2000). The 0.5–3 m in open shores. Below five me- geographical distribution of Fucus ve- tres the light intensity is near the pho- siculosus along the Finnish side of the tosynthesis compensation point of F. Baltic coast has not dimished since the vesiculosus and can restrict its growth old records of herbarium and literature. (Bäck and Ruuskanen 2000). Earlier, F. The distribution area of F. vesiculosus vesiculosus was recorded to grow at a reaches north up in the Gulf of Both- depth of 10 m in the Tvärminne archi- nia to the Quark and the northernmost pelago (Purasjoki 1935). In the Archi- localities are in Valassaaret and Rönn- pelago Sea, the continuous belt of F. skär. In the Gulf of Finland in the viciny vesiculosus nowadays reaches only from of Virolahti, F. vesiculosus thrives well depth of 1.0 to 4.0 metres, although in- and its distribution extends into the dividual plants may be found down to Gulf of Vyborg (Lehvo and Bäck 2000a). a depth of 7–8 metres (Mäkinen et al. F. vesiculosus thrives in several habitat 1994). types which can provide solid substrate. However, in some places Fucus Most vigorous Fucus belts were found vesiculosus was reported to grow to great on solid homogenous rock surfaces in depths in the 1990s. In the northern open shore areas. In sheltered shores it Quark Fucus has a total distribution of was found to grow on stones and could 0.6–8.4 meters, with low biomass in be restricted by soft sediments. comparison to that recorded in other General deterioration of the F. parts of the Baltic Sea (Bergström and vesiculosus belt is of great concern be- Björkvist 1997). In some places in the cause it is a key species in the Baltic Åland Archipelago it thrives depth of Sea ecosystem. An extensive decline of even 9 m (Ruuskanen and Bäck 1999). F. vesiculosus stands occurred in the southern and SW coast of Finland during the late 1970s (Kangas et al. 1982, Haahtela 1984, Hällfors et al. 7.3 Soft bottom 1984, Kangas and Niemi 1985). Espe- cially the F. vesiculosus belt disappeared vegetation almost completely from open archipelago shores and the abundance of F. ve- Zostera marina is the only phanerogam siculosus also decreased drastically species of marine origin in Finland. In along the open shores. The first signs these cold water it grows at its limit of of recovery were observed in the early distribution, but is an important key 1980s in the SW coast of Finland e.g. species as it creates small meadows Tvärminne archipelago. In the Archi- with a rich fauna (Lappalainen et al. pelago Sea, F. vesiculosus had also com- 1977, Boström and Bonsdorff 1997, Bos- pletely vanished from many localities tröm and Mattila 1999). The structure in the early 1980s (Mäkinen et al. 1984, (shoot density and biomass) of Zostera Rönnberg et al. 1985). By the late 1980s meadows in the Tvärminne area ap- (Rönnberg 1991) and the early 1990s pears to be rather stable in the longterm (Bäck et al. 1993b) it had partly recolo- (25 yrs), but the vegetation mosaic nised its former habitats, but the de- changes spatially through vegetative cline had continued in some parts of growth (rhizome elongation) (Boström the archipelago. 1996, Boström et al 1997). Flowering A survey of F. vesiculosus along the and fruit-bearing specimens have been southern coast of Finland showed that observed in the Åland Islands, but recovery of the species had occurred Zostera in the northern Baltic relies only on the upper part of the littoral. mainly on asexual (vegetative) repro-

The most vigorous growth occurred at duction (Boström 1995). ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 73 The bottom vegetation in shallow 7.4 Mass occurrences of areas can be dominated by Charophytes. Most Charophyte species occurring in macroalgae brackish water are rare and are included in threatened species. In many are- Drifting macroalgae have been encoun- as with dominance of Charophytes tered in the 1990s in the Archipelago there are high abundances of filamen- Sea and the Åland Sea and also in tous algae covering the bottom. Chara smaller amounts from the eastern Gulf baltica is possibly decreased during the of Finland to the sea area off Pori city. 1990s (Marja Koistinen, pers. comm.). When the filamentous macroalgae are Flads and gloes are common detached from the rocky shores they along Finnish coasts and in the archi- are transported to the sublittoral, where pelagos. They are shallow and shel- they can form loose-lying drift mats tered, clearly delimited water bodies, (Fig 7.1). As a result, the natural litto- either still connected with the sea or cut ral vegetation can be replaced and the off from it by land. They are often char- bottom fauna can be altered by an al- acterized by a well developed reed gal mat covering the available substra- zone and luxuriant submerged vegeta. It has been shown that with increas- tation. The species composition includes ing eutrophication drifting algal mats e.g. Fucus vesiculosus, Myriophyllum spp. increase, affecting the entire coastal and Potamogeton spp. With increasing food web. At present these algal mats isolation and decreasing salinity species are probably the main factor inducing such as Chara tomentosa, Najas marina hypoxia above the halocline in the ar- and Ruppia maritima become common chipelago area in the northern Baltic (Munsterhjelm 1996). Due to isolation Sea (Norkko and Bonsdorff 1996). the flads are subject to various threats. In the NW archipelago of the Mainly they are threatened by con- Åland Islands drift algae were found struction on the shore, boating and in many localities studied in 1995 dredging. (Holmström et al. 1997). The biomass increased drastically during the summer. The maximum biomass was 287 g

Fig. 7.1. Schematic presentation of the formation of the macroalgal mats. Part of the de-

tached filamentous algae floats on the shore and the major part sinks on the bottom. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

74 ○○○○○○○○○○○○○ The Finnish Environment 472 dw/m2 in August. The dominating species was Pilayella littoralis. Another study (Bonsdorff 1992) revealed that mats was dominated by the genera Stictyosiphon, Polysiphonia, Rhodomela, Sphacelaria, Pilayella, Furcellaria, Ceramium, Cladophora and fragments of Fucus. Loose-lying macroalgal mats with high biomasses of the species Entero- morpha sp. have been reported along the Finnish coastline (Koistinen 1987, Bäck et al. 1993a). In the archipelago off Rauma a free-lying flake form of Enteromorpha occupied a sheltered coastal area of the mouth of the Riv- er Eurajoki. A similar phenomenon of loose lying Enteromorpha has been recorded in the 1990s in the archipelago of Uusikaupunki (Lampolahti 1997). Enteromorpha was able to survive under the ice and exhibited vigorous growth as soon as the ice melted (Bäck et al. 1993a). On the northern side of the Hanko peninsula a large sandy area was covered by the Enteromorpha sp. in the inner archipelago. After reduction of waste water input, nearly all the Enteromorpha sp. was replaced first by Chara aspera and then by Cladophora glomerata in the early 1990s (Kautsky 1982). Mass occurrences of macroalgae can also be found outside obviously eutrophic estuaries. Ectocarpus siliculosus blooms in the SW coast of Finland have been suggested to be of wind-induced upwelling origin, exploiting short nutri- Dense accumulation of macroalgal mats on the sandy seashore can

ent pulses (Kiirikki and Blomster 1996). affect the recreational use of the shore. Photo S. Bäck ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 75 Drifting macroalgal mats: A CASE STUDY in 1996 Lehvo, A.and Bäck, S. (2001) with a small amount of black sediments and decaying filamentous algae were found In summer 1996 the macroalgal mats of the in 4 places. south-eastern Finnish coastal area from Several species of filamentous algae were Helsinki to Virolahti were mapped for the to form the mats. Macroalgae forming sin- first time. The project was carried out by gle-species mats included Vaucheria spp., the Finnish Environment Institute and the Cladophora glomerata, Fucus vesiculosus, fil- South-east and Southern Finland Regional amentous brown algae (Ectocarpus siliculo- Environment Centers. sus together with Pilayella littoralis), and En- Macroalgal mats of drifting algae were teromorpha. The following species were also found in 26 places of the 89 studied (Fig. found in mixed-species mats: Cladophora 7.2). The study revealed that mats normal- glomerata, Fucus vesiculosus, filamentous ly occupy rather shallow and sheltered ar- brown algae and Enteromorpha sp. Mixed- chipelago areas, or comparatively sheltered species mats were found in 7 places. The bays in exposed areas. The mats were found main species was Cladophora glomerata, only in areas of different types of bottoms, most- once filamentous brown algae were domi- ly sandy and silty. The mats were found in nant. Ceramium gobii was found in a mat water depths of 1 down to 10 meters, with always in association with other species. an optimum of 2–4 meters. Species in mats occurring more towards The occurrence of drifting algae form- the west were Cladophora glomerata and Ce- ing mats was often patchy. The sizes of ramium gobii. Species that occurred more patches varied from several cm2 to approx- towards the east were Fucus vesiculosus, imately 10 square meters. The thickness of Vaucheria and filamentous brown algae. the mats varied from 1 to 20 cm. Inside the Vaucheria spp. mats were found in an inner macroalgal mats some loosephanerogams archipelago, in sheltered muddy shores. Ce- were found, such as Zannichellia sp. and ramium gobii was found in mats only in an Ruppia sp. Under the mat, anoxic conditions outer archipelago, on rather exposed shores.

Fig. 7.2. Study area and sampling points in the Gulf of Finland in 1996. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

76 ○○○○○○○○○○○○○ The Finnish Environment 472 7.5 Littoral fauna 7.6 Decline of Mytilus edulis The littoral fauna communities of the Tvärminne area have exhibited remarkable long-term temporal changes The blue mussel, Mytilus edulis is one in species composition when compar- of the dominant animal species on sub- ing two large unpublished data sets littoral rocky bottoms from the west- from studies made in the early 1970s ern Gulf of Finland to the southern and 1980s. Four main changes were Bothnian Sea. Decreases in populations observed. The amount and biomass of of M. edulis have been reported in many filter feeders, such as Balanus improvis- areas of the Baltic Sea (Kautsky 1995). us and Electra crustulenta, increased, Changes in blue mussel populations both in relation to a certain area unit along the Finnish coast have been re- and in relation to the Fucus vesiculosus ported in 1990s, but virtually nothing biomass to which they were attached. is known about the long-term popula- Some species of marine origin, such as tion dynamics of M. edulis. The find- Idotea granulosa and Gammarus locusta, ings of Littorin and Gilek (1999) indi- benefited from the higher salinity. cate that the recolonisation of disturbed Some deposition feeders and species patches by M. edulis in the Swedish east feeding on filamentous alga also bene- coast is a relatively slow process. fited, e.g. chironomids. Limnic species, On the SW coast of Finland, M. such as Asellus aquaticus and Lymnea edulis biomass per area was about 5 peregra, declined due to slightly more times higher than in the outer the ar- saline water. However, in the middle chipelago off Porkkala, on the south of the 1980s, the species composition coast of Finland in 1996 (Hario et al. recovered towards the situation that 1999). Studies of M. edulis in the 1990s prevailed in the early 1970s, and ob- in the Tvärminne archipelago and west servations made in the early 1990s sup- of Hanko city demonstrated a consist- port this finding. ent trend towards decreasing mussel In the late 1990s the number of foul- size; the proportion of larger mussels ing species, such as Balanus improvisus in the population has decreased signif- and Electra crustulenta increased tempo- icantly since the 1970s (Sunila 1981, Öst rarily, especially in the very hot summer and Kilpi 1997). 1997 (Ari Ruuskanen, pers. comm.). A decrease in salinity during re- This was also the case with Cordylopho- cent decades may be the ultimate rea- ra caspia in the summer 1998. son for the observed changes, as salin- In the Tvärminne area compari- ity affects growth, maximum size and sons of Zostera marina-associated fau- reproduction success of mussels. Selec- na from 1968–71 to 1993 indicated an tive predation on larger mussels by ei- increased abundance and biomass of ders (Somateria mollissima) may be of the fauna, but a decreasing trend in local importance in this process (Öst species diversity. The total abundance and Kilpi 1997, Westerbom 1999). of zoobenthos has increased signifi- Roach (and flounder) also feeds exten- cantly in areas with sparse Z. marina sively on M. edulis. (Rask 1989) cover, and was more than three times Antsulevich et al. (1999) studied higher in areas with a dense vegetation the condition of the M. edulis popula- cover. The zoobenthic biomass doubled tion in the Seili area of the south-east- in the dense meadows, while no sig- ern Archipelago Sea in 1996. They nificant difference in terms of biomass found out that the Mytilus population was detected in the sparcely vegetated is quite stable and dense. In the S-part

areas (Boström et al. 1997). of the Archipelago Sea (Utö, Hitis), blue ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 77 mussel populations are stable and bio- lives in crevices of rocks and boulders masses per unit area are substantially and can only be observed by SCUBA higher than east of the Hanko penin- divers. Originally, the species was sula (Westerbom 1999). found in the Tvärminne-Tammisaari archipelago and near Dragsfjärd, but not from the western parts of the Ar- 7.7 Newcomers chipelago Sea, nor from the Helsinki- Porkkala area (Salemaa and Hietalahti The zebra mussel, Dreissena polymorpha 1993). More recently, H. anomala has was first recorded in the eastern parts been reported at several sites in the of the Gulf of Finland in 1995 (Valovirta western Gulf of Finland and the Archi- and Porkka 1996). In contrast to the main pelago Sea (Juha Flinkman, Mikko Kii- distribution areas of D. polymorpha, it rikki, Ilppo Vuorinen, pers. comm.). has not been recorded in fresh water During recent years the H. anomala areas in Finland. In other countries D. population has been increasing drasti- polymorpha has caused severe problems cally in these areas. in fresh water, e.g. in power plants by The origin of the Cladoceran strong settlement in the cooling water Cercopagis pengoi is in the Caspian and systems. The zebra mussel is now dis- Black Seas. It also lives in Lake Aral and tributed along the northern coast of the in estuaries of nearby big rivers such Gulf of Finland from the St. Petersburg as the Donau, Volga and Don. It is sug- region in the east to the Pellinki archi- gested that Cercopagis spread to the pelago in the west (Valovirta and Pork- Baltic Sea with the ballast waters of ka 1996, Välipakka et al. 1997). The boats travelling along the canals and abundance of D. polymorpha decreases rivers from Russia. The first observa- strongly westwards (Välipakka et al. tions of Cercopagis are from the Gulf of 1997). Hitherto, D. polymorpha has not Riga in Pärnu Bay in 1992. In Septem- been found to co-occur with Mytilus ber 1995 mass occurrences of Cercopagis edulis in the Finnish coast, and as a hard were observed in the eastern part of the bottom filter-feeding bivalve it seems Gulf of Finland. They were first record- to have occupied an open niche at least ed by fishermen who noticed that their in the eastern part of the Gulf of Fin- fishing gear and nets were full of land. In many sites in the Russian part Cercopagis. The species can reproduce of the Gulf of Finland D. polymorpha rapidly and when the water tempera- has become the dominant species on ture decreases Cercopagis forms resting the hard bottom (Välipakka et al. 1997). eggs which hibernate in the bottom A mysid, Hemimysis anomala, sediments. The distribution area ex- orginating from the Caspian Sea, was tends from the eastern part of the Gulf found in 1992 in the coastal waters of of Finland to the Hanko peninsula. It SW Finland (Salemaa and Hietalahti is thought that Cercopagis thrives well 1993). It is uncertain when the species along the south coast of Finland and

was introduced to this area, since it forms stable populations. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

78 ○○○○○○○○○○○○○ The Finnish Environment 472 Changes in zoobenthic

communities

○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 8

Pentti Kangas, Leena Byholm and Johanna Stigzelius

The following presentation on the state loading in the shallow sea area has and changes of zoobenthic communi- decreased markedly since the early ties in Finnish coastal waters is based 1970s, and that of phosphorus and ni- on the results of pollution control stud- trogen since the late 1980s (Haasala ies carried out every 3rd to 5th year in and Kauppinen 1995). The bottom fau- the 14 main loaded areas along the na communities in the innermost ar- coast, and on results of a long-term chipelago areas indicated that slight monitoring in one relatively clean area, eutrophication is still continuing. the Tvärminne archipelago, W of the However, the annual fluctuation of the Hanko peninsula. faunal abundances has decreased, which could suggest decreasing effects of waste waters in the inner archipela- 8.1 The Bothnian Bay go area. In the outer archipelago the increasing abundances of especially Tornio. The industrial input of nitro- oligochaets and chironomid larvae, as gen into the relatively open water area well as the appearance of C. plumosus- off Tornio increased during 1986-1996, type larvae indicate eutrophication. whereas the input of nickel, zinc and However, the abundance of M. affinis cyanide decreased compared to the late has not decreased, and thus the effects 1980s (Rantala 1997a). The bottom fau- of eutrophication changes do not yet na of the area consists of Monoporeia seem to be harmful. affinis, pisidiums, oligochaets and chi- Oulu. The direct discharge of par- ronomid larvae, but no clear gradient ticularly BOD7, but also of phosphorus can be seen from the sewers outwards. and nitrogen into the open sea area off In 1990, the total abundance of fauna Oulu has decreased from the early was at its highest during the 20 years 1980s to the early 1990s (Hökkä and of the survey. In particular M. affinis has Rantala 1991). There are only four zoo- become more abundant in the whole benthos surveys available from the area, as well as the oligochaets. Larvae Oulu area between the 1960s and 1991, of Chironomus plumosus- type indicat- but the results indicate eutrophication ing eutrophication, present in the ear- in both inner and outer areas (Kaup- ly 1990s, were not found in later inves- pinen 1991). Near the sewers the bot- tigations (Kauppinen 1997). The harm- tom fauna consisted mainly of oligo- ful effects of metals cannot be observed chaets and chironomid larvae in 1991, in the bottom fauna off Tornio. The whereas M. affinis occurred only in ar- abundances of fauna have not reached eas not receiving direct waste water the level which would indicate eu- load. A strong increase of faunal abun- trophication, nor have there been sig- dances, especially in the inner areas, nificant changes in the species compo- has been reported as a result of dimin- sition during the 1990s (Kauppinen ishing toxic effects of waste waters. 1995). Raahe. The direct discharges of

Kemi. The organic loading (BOD7) BOD7, phosphorus, suspended solids,

is discharged into the open areas and iron and oil into the relatively open sea ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 79 area have decreased significantly since coma balthica, whereas Monoporeia affinis the early 1970s. The nitrogen input in- was scarce. Further away from the sew- creased slightly during the 1980s but er the bottom fauna consisted mainly has remained relatively stable since the of Gammarus, Monoporeia and mysids. late 1980s (Kauppinen 1994). The abun- During 1990–1995 no essential chang- dance of zoobenthos increased during es in the state of the bottoms were re- 1978–1993. This was mainly due to the ported. increase of oligochaets and C. plumo- Pori. During the early 1990s the

sus-type larvae, whereas the abun- river loading of BOD7 and phosphorus dance of M. affinis decreased dramati- into the sea area decreased to one cally. These changes reflect increased fourth compared to the late 1970s. The eutrophication. industrial loading of ferrosulfate and Kokkola. During 1990-1994 the sulfuric acid also decreased markedly industrial loading of metals except for from the mean level of the 1980s (Ora- arsenic and cadmium decreased. There vainen 1996). According to a quality were no clear changes in the discharg- classification in 1994, badly polluted es of organic matter and nutrients dur- bottoms extended several kilometres ing that period (Kalliolinna and Aalto- from the factory sewer (Fig. 8.1a). Only nen 1995). The bottom fauna is very a few species occurred in this area and poor off Kokkola, partly due to the rel- even the shells of Macoma were badly atively small number of sedimentation corroded. Part of the bottom of the in- bottoms. In 1994 the bottom fauna was ner area was organically polluted dominated by oligochaets, whereas (Kärkkäinen 1995). Healthy bottoms while M. affinis occurred at only one occurred only in the open sea area, over moderately clean station. The decreas- 10 km from the sewers. The changes in ing abundance of this species and the the state of bottoms depend on the area. occurrence of C. plumosus-type larvae Some improvement in the state of the indicate deterioration of the bottom bottoms of the inner area occurred dur- fauna near the sewers during the early ing 1991–1996, especially near the fac- 1990s. However, dead bottoms were tory sewer (Vahteri 1997) and in the riv- not found. The great annual fluctua- er Kokemäenjoki estuary (Mankki tions of bottom fauna communities 1996). However, some organically pol- near the sewers indicated that the area luted bottoms further deteriorated dur- was already polluted in the late 1980s ing that time (Vahteri 1997). In the out- (Aaltonen and Kalliolinna 1990). er part of the middle archipelago, the area of healthy and semi-healthy bottoms slightly increased during the ear- 8.2 The Bothnian Sea ly 1990s. The biomasses decreased, mainly due to the succesful rejuvena- Kaskinen. The water area off Kaskin- tion of M. balthica. Populations of M. en is mainly open except for two bays affinis have also strongly increased. separated by sills. The main source of Thus the development in the sea area loading is a pulp and paper plant off Pori is very different to that in the which discharges its effluents to a Bothnian Bay, where the state of bot- semi-enclosed bay with no sills. The toms in the inner areas improved and industrial and municipal inputs of those in the outer areas deteriorated.

BOD7 to the area increased during Rauma. Direct loading to the ar- 1993–1995, whereas the loading of chipelago area off Rauma has de- phosphorus and suspended solids decreased markedly since the pulp facto- creased (Langi and Paavilainen 1996). ry closed down in 1991. The loads of

In 1995, the soft bottom fauna near the BOD7, phosphorus, suspended solids sewer indicated eutrophication. The and nitrogen have been lower in the bottom fauna was dominated by oli- 1990s compared to the 1980s (Jump-

gochaets, chironomid larvae and Ma- panen and Räisänen 1996). According ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

80 ○○○○○○○○○○○○○ The Finnish Environment 472 a b

c d

Fig. 8.1. Bottom quality classification at the sea areas off five coastal loaded areas, obtained by applying the system of Leppäkoski (1975) based on zoobenthos species composition and biomass. The figures are modified from Kärkkäinen 1994 (in Fig. a, Pori); Jumppanen and Räisänen 1996 (b, Rauma); Jumppanen 1997 (c, Uusikaupunki); Jump- panen and Räisänen 1997 (d, Turku); and Partanen 1993 (e, Kotka-Hamina. Quality

classes: I, healthy; II, semi-healthy; III, semi-polluted; IV, polluted; and V, very polluted. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 81 to the quality classification, the bot- ing the late 1980s. Meanwhile oligocha- toms near the sewers were badly pol- ets and chironomid larvae, indicating luted in 1994 (Fig. 8.1b). Abundances polluted bottoms, became more abun- were low and the fauna consisted of dant in the whole area. Although the only a few species. M. balthica domi- state of the inner archipelago improved nated the whole sea area and M. affinis during the 1990s, there was no im- was absent. The trends in bottom fau- provement in the state of the outer ar- na and seem to reflect the intensity of chipelago, despite the decreased phos- loading. From 1990 to 1994, the state of phorous load. This reflects the general the bottom communities somewhat eutrofication of the sea area, particu- improved in the inner archipelago are- larly in the outer archipelago (Jump- as and the area of strongly polluted panen 1997b). bottoms decreased. In 1990 the state of bottoms in the outer archipelago had deteriorated (Jumppanen and Mattila 8.3 The Turku area 1991), and the area of healthy bottoms decreased. However, in 1994 no further in the Archipelago Sea significant changes were observed. Uusikaupunki. The archipelago In that part of the sea area off Turku area off Uusikaupunki is relatively from where pollution control studies shallow and receives loads from a fer- are available, the exchange of water is tilizer plant, a municipal sewer the and limited by the wide and dense archi- river Sirppujoki, which discharges into pelago. The area receives loads from the area via a regulated freshwater ba- municipal and industrial waste waters sin. The industrial phosphorus loading and from the river Aurajoki. The direct has decreased markedly since 1993. phosphorus load was lower in the However, the background loading has 1990s than in the 1980s (Räisänen and evidently increased at the same time Jumppanen 1996). The phosphorus (Jumppanen 1997a). According to qual- load from extensive fish farming is ity classification, polluted or semi-pol- twofold that from sewage waters, and luted bottoms were located near the it is focused just on the production sea- outlets in 1996 (Fig. 8.1c). Benthic com- son. munities on these bottoms consisted Bottom quality classifications typically of Macoma balthica, polychae- have been carried out every fourth year ts (Nereis, Marenzelleria), oligochaets since 1956 (Räisänen 1997). Based on and chironomids. The semi-healthy the quality classification in 1995 (Fig. zone extended 8–10 km from the ferti- 8.1d), the bottoms between Naantali lizer plant and was densely inhabited and Parainen can be divided into three by Marenzelleria, a newcomer to the zones on the basis of dominant species. area. Healthy bottoms were found only Chironomus plumosus-type larvae, indi- at one station in the outer archipelago cating polluted bottoms, were domi- (Jumppanen 1997b). The state of the nant mostly in the sheltered areas. bottoms in the innermost area and in Macoma balthica, an indicator of slight- the inner archipelago somewhat im- ly eutroficated bottoms, dominated proved during the 1990s. Totally dead bottoms in the more open bays and bottoms were not recorded in the 1990s sound areas. In the outer archipelago and the zone of polluted bottoms de- the dominating species was Monoporeia creased in the areas where the phos- affinis. The effects of waste waters ex- phorus contents and primary produc- tended at most ca. 7 km from the sew- tion had been highest. Species indicat- ers in 1995. Dead bottoms were not ing healthy bottoms, such as M. affinis, observed in 1995, although signs of almost disappeared even from the out- oxygen depletion were observed espe-

er parts of the investigated area dur- cially in deep areas. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

82 ○○○○○○○○○○○○○ The Finnish Environment 472 There were no essential changes in the general state of the benthic fauna during 1983-1995, although some local changes were found. The state of the bottoms in the inner archipelago seems to have slightly improved from 1991 to1995, while the state of bottoms in parts of the outer archipelago deteriorated in 1995. The abundances of species typical for clean waters, such as M. affinis, decreased. A new species to the Turku region, Marenzelleria viridis, was found only in 1995. No clear trend in the status of the bottom existed between the different sub-areas. According to Räisänen (1997), an improvement in the state of Polychaete worm Marenzelleria viridis was recorded first time in 1990 bottoms of the Turku sea area in the in Finnish waters. Presently its distribution extends in the coastal near future is unlikely because of dif- waters from eastern Gulf of Finland to the Quark area. fuse loading from land areas and from Photo J. Stigzelius the Baltic Sea. It is more likely that the quality of bottoms will decline in areas now classified as healthy or semi- healthy. as. The state of the bottoms of the bays has slowly improved since the 1960s 8.4 The Gulf of Finland due to decreasing loading to these areas. No marked changes in zoobenthos Helsinki-Espoo sea area. In waters off occurred from the 1980s to 1997, al- Helsinki and Espoo the load imposed though abundances in most areas were by municipal sewage clearly exceeds highest in the early 1990s. In the outer that received from the river Vantaan- archipelago the dominating taxa are joki. The mixing conditions are rather also oligochaets and chironomids, but good, except in two semi-enclosed bays M. balthica became more abundant in into which a large part of the munici- the 1990s, while the numbers of Mo- pal waste waters were earlier dis- noporeia remained low. The abundanc- charged. Since 1987 most, and since es and biomasses were highest in the 1994 all, municipal waste waters of early 1990s, but decreased thereafter, to Helsinki have been discharged through be replaced mainly by oligochaets a tunnel to the outer archipelago 7 km (Norha 1998). The fluctuations in fau- from the coast. The waste waters of the na during past last ten years cannot be neighbouring town of Espoo have been explained by changes in direct loading discharged to the outer archipelago into the area, but more probably reflect since 1974. During 1987–1994 the direct the general state of the Baltic Sea. load of phosphorus received by the Porvoo. In addition to the waters Helsinki sea area decreased markedly of two eutrophicated rivers, Porvoon- and the BOD7 load slightly (Pesonen joki and Mäntsälänjoki, the Porvoo sea et al. 1995). According to annual sam- area is a recipient for municipal and pling of selected stations (Norha 1998), industrial waste waters. The munici- the bottom fauna of the inner bays con- pal waste waters are discharged into a sisted mainly of oligochaets and chi- semi-enclosed inner bay and the indus- ronomid larvae. Macoma balthica was trial waste waters into the more outer

found only the inner archipelago are- archipelago areas. The direct loads of ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 83 BOD7 and phosphorus have decreased the bottom fauna have further de- since the 1980s, while those from the creased. The explanation seems to be rivers have remained stable (Erkkilä that, due to the general eutrophication and Vaajakorpi 1993). Benthic commu- of the Gulf of Finland, the increase of nities on polluted bottoms of the Por- organic matter in the sediments made voo archipelago consisted mainly of C. the oxygen conditions of the bottoms plumosus-type larvae, oligochaets and unsuitable for most benthic animals. a few M. balthica individuals in 1992. The most significant change during the Tubificids, indicating polluted bot- 1990s on the species level was the toms, were particularly abundant in strong increase of Marenzelleria partic- 1992. Their increase suggests increased ularly near the cooling water outlet eutrophication in the whole area. The (Ilus 1997). bottoms in the outer area, Svartbäck- The Pyhtää-Kotka-Hamina re- inselkä, have been in very poor condi- gion. The coastal area covered by con- tion since the 1980s. At the shallower trol studies is more than 40 km in stations, the above-mentioned species width. The River Kymijoki discharges somewhat increased during the 1990s. into the sea as five bifurcations. In ad- At the deepest station, suffering sporad- dition to the river loads, the sea area ically from oxygen depletion, an ex- off Kotka, having limited water extremely scarce fauna was found in 1998 change conditions, receives discharg- (Erkkilä and Vaajakorpi 1999). M. affinis es from municipal sewers and from very strongly decreased throughout the wood processing industries. The sea whole outer area during the 1990s and- area off Hamina, to the east, receives was not longer recorded in 1998. discharges from wood processing in- Loviisa. Information is available dustries, municipal sewers and from from the middle archipelago, which the rivers Summajoki and Vehkajoki. receives domestic and process waste This area is also shallow and the bot- waters from a nuclear power plant. The tom consists of mud, thus being eu- total loading from the plant is rather trophicated by natural causes. Based low. The area is also influenced by a on the quality classification, most of the long fjord-like bay, and the discharges bottom near the coast from Pyhtää to of waste waters from the town of Lovii- Hamina was eutrophicated in 1992

sa. The BOD7 and nitrogen loads de- (Partanen 1993, Fig. 8.1e). The fauna on creased during the 1990s, whereas these bottoms consisted of oligochaets phosphorus loading slightly increased (Potamothrix hammoniensis) and chi- (Raita and Silvonen 1997). The diver- ronomid larvae (C. plumosus and Pro- sity of the bottom fauna is low. Near cladius spp). Toxic bottoms occurred the power plant, the dominant taxa near the industrial sewers. The abun- were the oligochaet Potamothrix ham- dance of oligochaets has increased in moniensis and the chironomid larvae in the eutrophicated zone since 1984, 1996. M. balthica was found in a few which suggests increasing eutrophica- areas. In all deeper and outer parts of tion in the inner archipelago. The ef- the investigated area the bottom fauna fects of waste waters extended to the was scarce or missing. Mainly chirono- outer parts of the archipelago, where mids and Marenzelleria viridis have sedimentation of organic matter caus- been found occasionally on these bot- es oxygen deficiency in some places. toms in the 1990s. M. affinis communi- Due to poor oxygen conditions the ties already disappeared in the late Monoporeia-Saduria communities in 1980s (Ilus 1997) and have been absent deep bottoms have become less fre- in the 1990s. The bottom fauna off Lovi- quent. The state of the outer archipela- isa was already found to be scarce in go deteriorated in the late 1980s (Mank- the past 1960s, but during the latest 20 ki 1990), but no further changes were

years the abundance and biomass of reported in 1992. In the latter survey ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

84 ○○○○○○○○○○○○○ The Finnish Environment 472 the network station had been extend- same stations were sampled already in ed outwards. Preliminary results (Kymi- the 1920s (Stigzelius et al. in prep.). The joen vesiensuojeluyhdistys ry) from the study area is situated in the outer ar- next survey with a wide station net- chipelago zone in a water body with work in 1997 reveal deterioration of good water exchange with the Gulf of bottoms. At eleven areas, mostly the Finland through a deep furrow. There outermost ones, the bottoms were has been no notable loading from lo- dead, and most stations situated some- cal point sources in the area, but the what inwards from these had only a trophic status has increased during re- very scarce bottom fauna. The reason cent decades due to general eutrophi- of deterioration for these coastal de- cation of the Gulf of Finland. pressions is most probably connected As is characteristic for the north- with over-eutrophication of the whole ern Baltic Sea, the number of benthic sea area, with an increase of sedimen- species found was low, 5 to 10 true tation and oxygen consumption on the benthos taxa per sampling occasion. bottoms. By contrast, the state of the The species composition was rather bottoms of some inner areas has im- similar throughout the study period. proved since the pollution load de- The bottom communities were domi- creased during the 1990s. nated by Monoporeia affinis and Macoma balthica at the 20 m station and by M. affinis and Pontoporeia femorata at the 35 8.5 Zoobenthos trends m station. A new species, Marenzelleria viridis, was first observed in 1990. It still in a reference area has low abundances, but appears to in Tvärminne have become a permanent member of the benthic communities. Long-term zoobenthos data is availa- Species composition, abundance ble from only one relatively non-pol- and biomass have changed considera- luted coastal area. Two sampling sta- bly from the 1960s to 1997 (Fig 8.2.). The tions, situated at Tvärminne Storfjärd populations of M. affinis showed a at the entrance of the Gulf of Finland, slight tendency to fluctuate with a 6–7 have been monitored since 1964. The year cycle. Similar fluctuations are also

Fig. 8.2. Total abundance of zoobenthos and the dominant species at 20 m depth in

Tvärminne from 1964 to 1997. Redrawn from Stigzelius et al. (in prep). ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 85 found in the open sea populations of 8.6 General zoobenthos the Gulf of Bothnia. The crustacea populations were strong until the 1970s, trends in the Finnish but have strongly decreased thereafter, coastal waters and were nearly absent in the late 1990s. However, the numbers of M. Pollution control studies are planned balthica and Halicryptus spinulosus, es- to assess the effects of waste waters on pecially the numbers of young individ- the state of receiving local areas, and uals, have increased at the 20 m sta- they are widely used for decisions tion during the 1980s. Macoma be- when planning water protection meas- came the dominating species, especial- ures. Thus, the studies have not been ly for biomass, at the shallower station planned to create a generalized picture in the 1990s. The change was similar, of the state of coastal bottoms through- but weaker at the 35 m station. The den- out the Finnish coastal area. Some un- sity of oligochaets at the 20 m station has certainties therefore remain when sum- decreased since the 1970s, whereas chi- marising the results for this purpose. ronomid larvae have increased in abun- This is mainly because less records dance in the 1990s. Densities of other available from reference areas and the species such as Pontoporeia femorata, Har- frequency of sampling in most areas is mothoe sarsi and Saduria entomon have only every 3rd to 5th year. However, it not significantly changed during the is possible to draw some conclusions. study period. There is no clear overall trend in The changes in the macrobenthic the state of the loaded bottoms along communities in the Tvärminne area the Finnish coast. The effects of waste probably resulted from the combined waters on bottoms are clear in areas effects of natural events such as intra- near the waste water outlets in all the and interspecific regulation, and eu- loaded areas, but the extent of effects trophication. The cyclic fluctuations in depends largely on both the amount the population of Monoporeia affinis and the character of loading and phys- were probably caused by intraspecific ical features of the area, such as the competition, whereas the decreasing shape of the coast, quality of bottom trend of density is possibly a conse- material and water exchange condi- quence of eutrophication. Results from tions. The areas with effects of waste the 1920s and 1930s, however, indicate waters on bottom fauna are particular- that eutrophication is not likely to be ly extensive in waters off Raahe, Pori, the main factor causing the decrease, Rauma, Turku and the Helsinki and since the populations were occasion- Kotka regions. ally very low in abundance even at that A considerable change, especial- time. Decreasing densities of M. affinis ly in coastal areas of the Gulf of Fin- have reduced predatory pressure on land, is the decrease of populations of Macoma balthica and Halicryptus spinu- Monoporoeia affinis at outermost sites of losus, allowing them to increase in the control programmes. The species number. strongly decreased or totally disappeared from all studied bottoms in the1990s or late 1980s. It is worthy of note that the development was similar in the Tvärminne area, which receives

very low loading and is generally con- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

86 ○○○○○○○○○○○○○ The Finnish Environment 472 sidered as a moderately clean area. This bottoms have deteriorated despite the change becomes much weaker through decrease in direct loading. Some dete- the Archipelago Sea towards the Gulf of rioration also occurred off Raahe, Kok- Bothnia. Changes in these areas are gen- kola and Kotka, whereas no clear erally weak, and in the northernmost changes were reported in sea areas off Bothnian Bay, off Tornio, M. affinis has Tornio, Oulu, Kaskinen and Pori. even increased in the 1990s. In the outer archipelago the devel- Another important feature in the opment was more consistent. In most species composition of the coastal wa- areas there were changes towards poor- ters of Finland is the introduction of a er quality during the early 1990s and new species, the polychaet Marenzelleria often already in the late 1980s. Most of viridis. The species was first detected the changes were interpreted to be rath- in 1990, and it has in places become er weak. A typical sign of this was the abundant during the early 1990s. It decrease of Monoporeia affinis, which in- seems to favour slightly eutrophicated dicates clean waters, while the abun- bottoms and, as an expansive species, dances of oligochaets and chironomid it may displace weaker species (Stig- larvae increased. This development has zelius et al. 1997, Ilus 1997). However, been strongest in the Gulf of Finland. the actual effects of this polychaet on Signs of improvement in the state of the other species are not yet known. outer archipelago around the Finnish In order to illustrate the possible coasts were detected only off Pori. general trend in the state of Finnish coast- When the state of bottoms in the al zoobenthic communities, a compila- inner archipelago has improved coin- tion based on conclusions drawn by the cidently with decrease in the point authors of the pollution control reports source loading, this decrease does not was made. Because the frequency and seem to be able to account for the im- intensity of studies vary between the provement recorded in the state of bot- individual areas, the result (Table 8.1) toms in the outer archipelago more dis- is not very accurate and it should be tant from the sewers. As shown above, considered mainly as indicative. De- the state of the bottom fauna in these velopments in the quality of bottom areas has become poorer, and therefore fauna have been quite different in dif- must be due to some other reason than ferent loaded areas during the past 20 the effects of waste water loading. years. There are no signs that harmful sub- In the inner archipelago areas near stances have such wide effects on the the loading sources the development fauna, but rather eutrophication of the is most diverse. The direct load of par- Baltic Sea, manifesting as increased ticularly BOD7 and phosphorus de- production, sedimentation and oxygen creased in most of the controlled areas consumption on the bottoms, is seen during the 1980s and early 1990s. Off as the most obvious reason for deteri- Kemi, Rauma, Uusikaupunki, Turku oration of the fauna in the outer coast- and Helsinki there has been clearest al areas. Decline in species diversity improvement in the state of the most and abundance in these bottoms is loaded inner areas. This appears e.g. as strongest in those coastal areas which a decrease in the zone of polluted bot- have the highest degree of trophy (see tom, and as an increase of other ani- Chapters 5 and 6), especially in the mal groups than oligochaets and chi- Gulf of Finland.

ronomids. Off Porvoo and Loviisa the ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 87 Table 8.1. Changes in state of zoobenthos near the loading sources in the inner archipelago and in the outer archipelago of fourteen loaded coastal areas in the 1980s and 1990s. The conclusions are based on reports of corresponding control study programmes. Sea area Inner archipelago Outer archipelago Coastal area early late early early late early 1980s 1980s 1990s 1980s 1989s 1990s Bothnian Bay Tornio 0 0 0 0 0 0 Kemi 0 (+) + 0 0 – Oulu + + 0 .. 0 0 Raahe (–) – (–) (–) – (–) Kokkola + (–) – .. 0 –

Bothnian Sea Kaskinen 0 – 0 0 .. 0 Pori + 0 +/– 0 0 (+) Rauma + +/– (+) 0 – 0 Uusikaupunki 0 – + + – 0

Archipelago Sea Turku region 0 0 (+) 0 0 (–)

Gulf of Finland Helsinki-Espoo 0 (+) + 0 (–) (–) Porvoo 0 0 (–) 0 0 (–) Loviisa 0 0 – 0 0 – Kotka region + – – 0 – 0 The symbols indicate: + improving bottom state – deteriorating bottom state +/– partly improving, partly deteriorating 0 no significant changes detected ( ) the development is unclear or weak .. the development of the state of the bottom is not stated in the report,

or the investigation has not been done. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

88 ○○○○○○○○○○○○○ The Finnish Environment 472

Fish and fisheries

○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 9

Antti Lappalainen & Martti Rask, Finnish Game and Fisheries Research Institute

The number of regularly occurring fish wild salmon stocks of the Bothnian Sea species in Finnish coastal waters is ap- are further threatened by the M-74 syn- proximately 60 excluding the intro- drome affecting the survival of yolk- duced species. However, the majority sac fry. The mean mortalities of salm- of fish species are small-sized or scarce- on yolk-sac fry hatched from eggs col- ly occurring species and therefore not lected from the females ascending riv- important for the fisheries. As a conse- ers after feeding migration in the Bal- quence, there is very little information tic Sea have varied from 50 to over 90% about the stocks of these species, al- in recent years. The cause of this syn- though they may be important compo- drome is still unknown. The toxicants nents of the coastal ecosystems. The or changes in the food webs in the feed- status and changes in the stocks are ing area of salmon (the Baltic proper) generally better known for the 10-20 have been proposed as potential caus- species important for fisheries. Coast- es (Vuorinen et al. 1997). al fish species are usually classified as In addition to salmonids, some migratory, limnic or marine species cyprinids are also present only as mi- according to their original adaptation gratory species in our coastal waters. to salinity. This classification is also It is evident that the deterioration of the useful when considering the connec- spawnig rivers and brooks has nega- tion between coastal water quality and tively affected the stocks of vimba fish stocks. Deterioration in coastal (Vimba vimba) (see Saulamo and Lehto- water quality may also have direct ef- nen 1998) and the commercial cathes fects on fisheries as discussed in sec- of ide (Leuciscus idus) from the begin- tion 9.4. ning of 1980s. The decrease of ide stocks in the Helsinki region (Anttila 1973) could be partly explained by the 9.1 Migratory species same cause.

The stocks of migratory species, such as salmon (Salmo salar), trout (Salmo trutta) 9.2 Limnic species and migrating whitefish (Coregonus lavaretus), were strongly affected by the The effects of eutrophication and pol- damming and pollution of most lution of coastal waters on fish stocks spawning rivers in the first half of the are most clearly seen among the lim- twentieth century. There is no evidence nic species, which permanently live and that the state of the coastal area itself spawn near the coast and in the archi- has had any major effects on these pelago zone. There are a few observations stocks, which are now depent on stock- of increased abundance of cyprinids, ing programs. At present, reared fish especially roach (Rutilus rutilus). Paavi- account for 80–90% of the Finnish lainen et al. (1985) carried out test fish- salmon and migratory brown trout ings in the eastern Gulf of Finland and catches, and 65% of the migratory found highest proportions of cyprinids

whitefish catch in the Baltic Sea. The and ruffe (Gymnocephalus cernuus) in ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 89 monitored since 1992 with gill nets. Roach was rare in the beginning of the period, but has become increasingly more common. (Ådjers et al. 1997). Unfortunately, general trends in roach catches are not available as roach is not accurately recorded in the commercial catches. The sea area close to Helsinki city has been one of the most polluted along the Finnish coast, especially during the late 1960s and early 1970s when the wastewater load on the adjacent bay areas of Helsinki was at its maximum. The deterioration in water quality was clearly reflected in local fish commu- Fig. 9.1. The commercial catches of pikeperch (Stizostedion lucioper- nities. Anttila (1973) reported that the ca) in the Archipelago Sea and in the Gulf of Finland during 1980–1998. local whitefish, burbot (Lota lota) and pike (Esox lucius) populations had decreased or disappeared, and specially roach (Rutilus rutilus), ruffe (Gymnocephalus cernuus) and white bream (Blicca bjoerkna) the most polluted areas. Bonsdorff et populations had increased. Pike-perch al. (1997a) monitored the fish commu- (Stizostedion lucioperca) and bream (Abramis nity structure of an inshore area of the brama) populations also withstood pol- Åland Archiplago during 1975–1994. lution rather well. Later, during the They showed that roach has increased past 20 years, the water quality in the from below 15 to ca. 45% of the total bay areas of Helsinki has improved biomass, reflecting the ongoing eu- considerably but Lappalainen and Pe- trophication. In the Tvärminne region, sonen (1998) showed that the recovery western Gulf of Finland, a strong in- in local fish communities in the bay crease in roach stocks occurred place area west of Helsinki has been very during the past 25 years. In 1975, roach slow. Cyprinids and ruffe still account- was abundant only in the innermost ed for about 80% of summer test fish- areas of the local archipelago. In 1997, ing catches in 1997. It is evident that however, roach was the most abundat white bream is the cyprinid which species in the innermost areas but also withstands or even benefits most from in the outer archipelago of Tvärminne. extremely eutrophic conditions (Lap- The growth rate of roach has decreased, palainen and Pesonen 1998). It was indicating increased competition for earlier the dominant species in the test food (Lappalainen et al. manuscript a). fishing catches from the most polluted A gill net survey conducted in summer part of the bay area west of Helsinki 1998 revealed that roach is abundant but more recently its proportion has in the intermediate and outer archipel- decreased. ago throughout the whole northetn Lehtonen (1985) suggested that coast of the Gulf of Finland from the pike-perch stocks have even in- Hanko to St Petersburg (Lappalainen creased in the southern coast of Finland et al. manuscript b). At present, slow due to eutrophication. The annual increase in roach abundance appears commercial catches of pike-perch from to be occurring in the southern Archi- the southern coast have at least dou- pelago Sea. The warm water fish com- bled during the past 20 years (Fig. 9.1) munity structure in Brunskär in the but the fishing effort has simultaneous-

southern Archipelago Sea has been ly also increased. However, summer ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

90 ○○○○○○○○○○○○○ The Finnish Environment 472 temperature is an important factor de- caused damage to local fish stocks. In temining the year-class strength of the estuary of the river Kyrönjoki, for pike-perch and perch (Perca fluviatilis) example, this has resulted in irregular in our coastal areas (Wiik and Kuikka fluctuations and decreases of burbot 1998, Böhling and Ådjers 1998). Strong and perch stocks (Kjellman et al. 1994, year classes of pike-perch developed in Hudd et al. 1996). 1988, 1991 and 1994. The peak in commercial catches of pike-perch was in 1997 as the year class of 1988 was still 9.3 Marine species abundant whereas the year class of 1991 was recruited to fisheries (Wiik Baltic herring (Clupea harengus) is the 1999). In the gill net survey conducted most important marine species for in 1998, the mean perch catches were Finnish commercial fisheries as it ac- approximately threefold higher near counts over 80% of the weight of the the western coast of the Gulf of Fin- annual total catch. During the 1990s the land than in the eastern parts of the gulf herring stocks have been on a normal (Lappalainen et al. manuscript b). The level as measured by numbers of indi- higher turbidity and resulting vertical viduals. However, the growth of Bal- narrowness of the littoral and the lack tic herring has decreased dramatically of a bladderwrack (Fucus vesiculosus) (Pönni 1998a). Weight-at-age of the belt in the eastern gulf might restrict Baltic herring was high in the begin- the food supply and abundance of ning of the 1980s, but has since de- some species such as perch. Koli et al. creased, being now less than half of the (1988) showed that macrocrustaceans earlier level (Fig. 9. 2). The biomass of were the most important food for perch the spawning stock has also decreased. (10-20 cm) in the western Gulf of Fin- Flinkman et al. (1998) showed that the land. The bladderwrack belt is impor- biomass proportion of larger zooplank- tant for macrocrustaceans and small ton preferred by herring has declined fish, as it offers them both food and in the northern Baltic Sea due to slight shelter. However, the general decline in bladderwrack in the southern coastal waters of Finland (Kangas et al. 1982) and the raise of the lower limit of the bladderwrack dominant zone (Kautsky et al. 1986, Bäck and Ruuskanen 2000) might have affected the fish populations. These changes on bladderwrack have been attributed to increased nutrient concentrations and subsequent changes in ecosystems. Koivisto and Blomqvist (1988) studied the effects of fish farming on local fish communities in the Archipel- ago Sea. They showed that fish farming can cause changes in species composition towards a greater number of cyprinids, especially roach and white bream, in the immediate vicinity of the farms. Henriksson (1991) showed that ruffe and perch also occurred in large numbers close to the farms. In certain Fig. 9.2. The mean weight of herring at ages 1,2,4,6,8 and 10 years in areas of the west coast, soil-induced the Baltic Proper, Archipelago Sea and Gulf of Finland during 1974–

acidification of rivers and estuaries has 1997 (Pönni 1998a). ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 91 decrease in salinity, which is one rea- Baltic Sea and the state of the stocks is son for the recent decline in herring largely determined by the conditions growth. The changes in water quality in the spawning areas. The recruitment might have some local effects on the of these species is mainly affected by reproduction of herring, as the most large-scale changes, such as salinity, important spawning grounds are locat- oxygen conditions (Aro 1998) and posed in the archipelago zone. Anttila (1973) sibly the general eutrophication of the reported that the spawning grounds of Baltic Sea. The fishing pressure on the herring moved outwards from the cod stocks in the southern Baltic is too shore due to increased pollution in the high as compared to the current status Helsinki region during the 1960s. of the stocks (Aro 1998). Kääriä et al. (1988) showed that the eutrophication has had adverse effects on the spawning grounds of herring 9.4 Direct harmful and on herring fisheries in the inner parts of the Archipelago Sea. Howev- effects on fisheries er, Parmanne (1999) found no general changes in the spawning areas of her- Eutrophication and pollution of coast- ring in the Finnish coastal zone dur- al water has caused some direct harm- ing the period 1974–1989. Normally, ful effects on fisheries. Strong fouling egg mortality of herring is considered or sliming of passive gear – especially to be less than 10%. Rajasilta et al. gill nets – is the most prominent prob- (1989) observed far higher mortalities lem in recreational fisher caused by in situ in the inner Archipelago Sea, in eutrophication. Strong fouling or slim- some spawning substrates even ex- ing of gear was experienced by 67–86% ceeding 90%. However, the potential of all recreational fishermen in a mail consequences of the changes in spawn- survey conducted in three study areas ing grounds and nursery areas on the in the Gulf of Finland (Lappalainen stock level are unknown. and Pönni 1996). This is also a well- Flounder (Platichtys flesus) and known problem e.g. in commercial turbot (Psetta maxima) are also marine salmon trap fisheries. It causes extra species spawning in the archipelago work for fishermen and can decrease zone. Aarnio and Bonsdorff (1997) re- the efficiency of gear. The water cur- ported that the increasing eutrophica- rents and waves carry loose filamen- tion of the coastal waters of the Baltic tous macroalgae and loose brown al- Sea favours prey species (e.g. Ostraco- gae (Fucus vesiculosus) to passive gear, da, Hydrobia spp.) that are non-diges- especially to those set on the bottom. table for juvenile flounder. Further- The filamentous green alga, (Cladophora more, roach feed mainly on molluscs glomerata), is the dominant littoral mac- in the southern coastal waters of Fin- roalgae in the northern Baltic Sea, and land (Rask 1989, Lappalainen et al. the growth of it has increased due to manuscript a) and thus the increased eutrophication of coastal areas. The roach stocks utilize the same food re- increased production of filamentous sources than flounder. At the end of algae has even led to a strong increase 1990s the stocks of cod (Gadus morhua) in benthic drifting algal mats, covering in our coastal waters were very weak large areas of intermediate depths (Aro 1998) and, on the other hand, the (Bonsdorff et al. 1997b). The increased stocks of sprat (Sprattus sparttus) were primary production of small algae abundant (Pönni 1998b). The main causes further sliming of gill nets and spawning areas of these two marine traps, and in the Gulf of Finland mass

species are situated in the southern occurrences of the alien predaceous ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

92 ○○○○○○○○○○○○○ The Finnish Environment 472 cladoceran (Cercopagis pengoi) during the late 1990s have also had similar effects on passive gear. Off-flavours or -odours in fish have been a common problem in some se- verely polluted areas (Fig. 9.3). For example, Paavilainen et al. (1985) showed that off-flavours in bream and pike were common in some of the most polluted areas close to Kotka, the eastern Gulf of Finland, but they associated these mainly with the effects of pulp and paper mill effluents. In the Helsin- ki region, off-flavours in fish were obviously more common over 20 years ago when the municipal waste waters Fig. 9.3. Harmful environmental effects. were discharged into inner bays around Helsinki. According to a local questionnaire carried out in 1969, as many as every third recreational fish- erman had noted clear off-flavours in caught from three study areas in the bream, perch, pike-perch or roach Gulf of Finland (Lappalainen and Pön- caught in the Helsinki region (Anttila ni 1996) and 5–20% indicated a high 1973). In a survey conducted in 1994 abundance of less wanted species, such only 5–10% of recreational fishermen as cyprinids, ruffe and smelt (Osmerus reported off-flavours or -odours in fish eperlanus) in gill net catches.

Fouling of gear is caused either by drifting filamentous macroalgae or plankton.

Photo R. Yrjölä ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 93

Harmful substances

○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 10 ○○○○○○○○○○○○○○

Markku Korhonen, Matti Verta, Viveka Backström

10.1 Heavy metals The concentrations of mercury are highest in the Bothnian Bay and of cadmium in the Gulf of Finland. Lead and 10.1.1 Sediment mercury concentrations are lower in the Baltic Proper than in the Gulf of There are considerable variations and Finland and the Gulf of Bothnia (Lei- regional differences in the concentra- vuori 1998). The mean concentrations tions of heavy metals in the surface in the open sea area are within the sediments of the Gulf of Finland and range typically measured in the Baltic the Gulf of Bothnia (e.g. Leivuori 1998). Sea and clearly higher compared with The distributions of three non-essen- the pre-industrial level for all these tial and toxic metals (Pb, Cd, Hg) show three metals (Table 10.1). a decreasing trend from north to south Several industrial plants are locat- in the Gulf of Bothnia, and from east ed in the coastal area of Finland. This to west in the Gulf of Finland. The is usually reflected as elevated metal mean concentrations of lead in the sur- concentrations in the sediment in are- face sediment were 50 mg kg-1 dry as close to their effluent sources. The weight (dw) in the Gulf of Finland, 79 individual maximum metal concentra- mg kg-1 in the Bothnian Bay and 42 mg tions in the surface sediments are kg-1 in the Bothnian Sea. Mean concen- shown in Table 10.1 (Finnish maximum trations for cadmium were 1.1, 0.9 and values in 1990s). Clearly higher con- 0.4 mg kg-1 dw and for mercury 0.1, 0.3 centrations than “typical” are meas- and 0.1 mg kg-1 dw. ured for each metal on some occasions.

Table 10.1. Examples of trace metal concentrations in sediments of the Baltic Sea (mg kg-1 dry weight), modified from Sternbeck et al.(1999). Present extremes represent Finnish data from surface sediments during the 1990s. Metal Preindustrial Typical Baltic Present extreme extreme Cd 0.2-0.8 0.3-5 100 8.2 Cr 20-50 20-200 800, 11000 128 Cu 30-50 30-80 1200 450 Hg 0.02-0.04 0.05-0.8 100 13.6 Pb 4-30 40-200 25000 240 Zn 70-150 150-500 50000 920 Data compiled from Swedish EPA 1991, Holm 1988; Östlund et al. 1998; Borg and Jonsson 1996; Perttilä and Brygman 1992, Leivuori and Niemistö 1995, Lapp and Balzer 1993. Finnish maximum values in 1990s are from Kyröläinen 1995, Piiroinen 1992a, Kalliolinna and Aaltonen 1995, Jumppanen 1993, Pesonen 1988, Varmo and Riiheläinen 1991, Lehtoranta,

not published, Partanen 1991, Miettinen et al. 1994. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

94 ○○○○○○○○○○○○○ The Finnish Environment 472 However, these are far below the Bal- emissions of chromium from the plant tic extreme concentrations. have increased in recent years com- For mercury notably high mean pared to the early 1990s (Finnish Envi- concentrations can be seen in the river ronment Institute). The sediments off Kokemäenjoki and its estuary, with a Rauma and in the river Kokemäenjoki maximum of 13.6 mg kg-1 (Piiroinen (leather factory) also have local high 1992a). This area has a history of high chromium concentrations (Piiroinen heavy metal loads from the industry 1992a, Lounais-Suomen vsy 1995). located along the river. Metals have The titanium dioxide factory in been emitted e.g. from a chlor-alkali Pori began operations in 1961. This fac- plant, a fertilizer plant, a copper smelt- tory uses sulfuric acid and an iron ore er and a leather factory. The load of to produce titanium oxide. The dis- metals has decreased considerably charges of sulfuric acid and metals since the 1970s and 1980s. Other re- have decreased as a result of improve- gions with elevated mercury concen- ments in waste water management. trations are Oulu (a chlor-alkali plant), Consequently, concentrations of titani- Kokkola (Kalliolinna and Aaltonen um and vanadium in surface sedi- 1995) with fertilizer and chemical pro- ments have decreased since the early duction (see also section 8.2.2) and re- of the 1990s (Patrikainen 1991). gions with pulp and paper production (eg. Oulu, Rauma, Kotka). In these locations mercury partly originates from 10.1.2 Zoobenthos its former use as a fungicide. Concentrations of cadmium in Metal emissions from industries are sediments from all locations are typi- usually reflected in higher concentra- cal for the Baltic Sea, with no extreme tions of different metals in zoobenthos values reported. However, elevated dwelling in the contaminated area. cadmium concentrations compared Heavy metal concentrations in Baltic with preindustrial levels can be seen mussel (Macoma balthica) have been in most locations under monitoring. used for monitoring purposes in the The importance of point-source sea areas off Vaasa, Rauma, Koverhar loads of lead from industries is mar- and Pori (Häkkilä 1985, Kokemäenjoen ginal for the total lead flux to the Bal- vsy 1995, Kyröläinen 1996, Miettinen tic compared to atmospheric deposi- et. al. 1993). Although, according to tion and the loads from rivers (Enck- these authors, Macoma in the sea area ell-Sarkola et al.1989). Elevated concen- off Vaasa show increased concentra- trations can be seen in the Helsinki re- tions of chromium (1.8–4.1 mg kg-1 dw) gion due to traffic emissions (Varmo and and lead (0.9–1.7 mg kg-1 dw) and Riiheläinen 1991) and near steel plants Macoma from Koverhar increased con- in Uusikaupunki (Partanen 1991) and centrations of cadmium (1.3–2.3 mg kg- Koverhar (Miettinen et al. 1994). 1 dw, Lounais-Suomen vsy 1995; Kalli- The highest copper concentra- olinna and Aaltonen 1995), none of tions in bottom sediments occur in these concentrations can be considered Rauma, where machinery plants and as extremely high. Reference data from docks are located (Lounais-Suomen the Baltic Sea area is scarce, but com- vsy 1995). High copper concentrations parison with extensive data from blue are also found in the river Kokemäen- muscle (Mytilus edulis) from the Arctic joki sediments and in sediments from indicates that none of these concentra- the Helsinki area (Piiroinen 1987, tions differ significantly from back- 1992a, Pesonen 1988). ground variation (data from the Arctic Generally, highest concentrations is on a wet weight basis, HELCOM of chromium have been measured near 1996, AMAP 1998). Mercury concentra-

a stainless steel plant in Tornio. The tions in blue mussel from the river ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 95 Fig. 10.1. Concentration of some heavy metals in Saduria entomon from the sea area off Kokkola during 1976–1992 (Data from Kalliolinna & Aaltonen, 1995).

Kokemäenjoki estuary indicate con- 10.1.3 Hg in fish tamination (0.17–1.24 mg kg-1 dw) compared with Hg in blue mussel in the Mercury concentrations in fish in are- Arctic (<0.003–0.061 mg kg-1 ww, as with high Hg pollution during the AMAP 1998) or from the Kattegat – 1960s and 1970s have decreased con- Swedish west coast region (< 0.03 mg siderably. Mercury concentrations in kg-1 ww, HELCOM 1996). pike muscle have decreased from a lev- At certain locations Saduria ento- el of 1 to 2 mg kg-1 to below 1 mg kg-1 , mon is used for monitoring of metals which is the maximum level for human in biota. Fig. 10.1 shows a decrease of consumption, in all areas under moni- copper, cadmium and mercury but not toring. At the beginning of the 1990s of Zn and As in Saduria caught in the the mean concentrations of mercury in sea area off Kokkola from 1976 to 1992 all polluted coastal areas were 0.63 mg compared to Saduria from a clean area, kg-1 ww (min 0.31, max 1.39), which is Pyhämaa (Kalliolinna and Aaltonen only somewhat higher than in refer-

1995, Figs. 10.1 and 10.2). ence areas 0.52 mg kg-1 ww (min 0.17, ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

96 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 10.2. Localities of the sampling sites of harmful substances in this study.

max 0.90). No significant change can The mercury concentrations of be detected during the 1990s in most Baltic herring (Clupea harengus) in Finn- areas, except for a small decrease at the ish sea areas are below 0.05 mg kg-1 ww most contaminated stations (Figs. 10.2, in the Baltic Proper and in the south- 10.3). ern area of the Gulf of Finland (HEL- Mercury data for other predatory COM 1996, Jankovski et al. 1996, Lei- fish species is rare, but indicates that vuori et al. 1997). For monitoring pur- particularly in burbot (Lota lota) and poses two-year, non-mature females perch (Perca fluviatilis) the level of 0.5 are used. The highest levels of mercu- mg kg-1 (the maximum level for other ry are found in the eastern part of the species than pike) may be exceeded in Gulf of Finland. older and larger individuals in areas with former Hg pollution (e.g. Verta et

al.1999c). ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 97 Fig. 10.3. The mercury concentrations in pike in coastal areas. (FEI monitoring data. Piiroi-

nen 1992, Hakaste and Piiroinen 1997) ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

98 ○○○○○○○○○○○○○ The Finnish Environment 472 10.2 Organic pollutants Since 1986 effluent has been treated in a secondary activated sludge plant. 10.2.1 Sediment Presently oxygen and chlorine dioxide are used for bleaching. A clear change The concentrations of polychlorinated in the amount of sedimented chlorin- dioxins and furanes (PCDD/Fs) varied ated organic material, measured as from 130 to 680 pg g-1 dry weight, (dw) EOX or as chlorophenoles, could be ITEQ in the vicinity of the vinylchlo- seen, reflecting changes in the bleach- ride monomer production plant at ing processes. Sköldvik on the Gulf of Finland (Var- The concentrations of EOX (30– tiainen et al. 1997) and up to 1820 pg g-1 180 mg Cl kg-1) in top sediments from ITEQ in a sediment core (Isosaari et al. stations close to pulp mills in Kotka, 1999). These are the highest reported Kemi, Pietarsaari and Rauma in the sediment PCDD/F concentrations in 1990s (after process changes had been Finnish coastal areas. In the Bothnian made in the pulp mills) are considera- Bay about 350 pg g-1 dw ITEQ was re- bly lower than were reported in the ported close to a pulp and paper mill 1980s when chlorine bleaching was in Pietarsaari. generally used. EOX-concentrations of Up to 6-7 kg of PCDD/Fs (as up to 2000 mg Cl kg-1 were reported for ITEQ) has ended up in the Gulf of Fin- sediments near pulp mills in Sweden land since 1940 in the estuary of the (Södergren 1989). river Kymijoki, south-eastern Finland, At present, natural organohalogen mainly due to production of the wood production appears to be the major preservative Ky-5 in the upper region source of the EOX in the Gulf of Fin- of the river (Verta et al. 1999a,b). This land. Specific organochlorine and pulp is clearly seen as increased PCDD/Fs mill effluents are responsible for only concentrations in surface sediments a minor part of the total EOX. EOX is (up to 200 pg g-1 dw ITEQ). The load of produced predominantly during the PCDD/Fs to the estuary has decreased spring diatom bloom. As anthropogen- only slightly during the past 30 years, ic input decreases, the share of natural as measured from the sediment profile production in the total EOX budget will (Verta et al. 1999c). Increased concen- increase (Kankaanpää 1997). trations of polychlorinated phenols (PCPs) and polychlorinated diphenyl ethers were also measured (Verta et al. 10.2.2 Zoobenthos 1999a,c). As a result of the decreased use of chlorine in bleaching, and other Generally concentrations of PCBs and improvements in waste-water manage- DDTs in Baltic mussel (Macoma balthica) ment, a greatly decreased discharge of are higher (2–3 fold) compared with the chlorinated organic compounds can be few available analysis in Macoma sp. noted. in the Arctic area in Kara Sea, Russia The decreased discharge of orga- (PCB 3.5 and DDT 1.3 ng g-1 ww, AMAP nochlorines from pulp mills is reflect- 1998). Even higher concentrations have ed as decreased concentrations of these been measured elsewhere in the Bal- compounds in sediments close to pol- tic; in the Swedish east coast (Tema lution sources. Palm and Lammi (1995) Nord 1994) and in the southern area of studied the deposition of AOX and EOX the Gulf of Finland (Roots 1996). Ac- (Extractable Organic Compounds) and cording to monitoring data from two different organochlorines specific to stations both PCB and DDT concentra- bleaching effluents at some stations tions are somewhat lower in the south- near a pulp mill in Pietarsaari. The use ern Bothnia Bay (Mikkelinsaaret) than

of chlorine chemicals started in 1976. in the western Gulf of Finland (Tvär- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 99 Fig. 10.4. The concentratins of PCB and DDT (ug/g ww) in Macoma balthica from 1988 to 1997 in the coastal areas Tvärminne (Gulf of Finland) and Mikkelinsaaret (Gulf of Bothnia).

minne) (Fig. 10.4). In Tvärminne PCB 10.2.3 Fish and DDT concentrations were considerably lower in 1997 than in the early PCB and DDT 1990s and particularly in the late 1980s. Annual monitoring of PCB and DDT No decreasing trend of PCB and concentrations in young Baltic herring DDT was observed in M. balthica in the Clupea harengus (two-year, non-mature Mikkelinsaaret area from 1988 to 1994, females) before their migration to feed- but further development is uncertain ing areas has been conducted by the due to lack of data (Figs. 10.2, 10.3). The Finnish Marine Research Institute. The area is at the limit of distribution of M. PCB and DDT levels have been rather balthica in the diminishing salinity, and constant and somewhat higher (range makes interpretation of the monitoring 6–15 ng g-1 ww for PCB and 2–16 for results difficult. The reason for the in- DDT compared with those in Atlantic crease in total DDT from 1988 to 1994 herring (Clupea harengus) in the Arctic is mainly due to the isomers DDD and Sea (Iceland) ( PCB 3.8–11 ng g-1 ww DDT. However, the isomer DDE still and DDT 2.7–8.1 ng g-1 ww, AMAP dominated in mussels from the Gulf of 1998). Only slight decreases in concen- Bothnia in 1994. The dominating PCB trations of both PCB and DDT have congeners have been 153 and 138 been observed since the late 1980s

(IUPAC). (Finnish Marine Research Institute). ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

100 ○○○○○○○○○○○○○ The Finnish Environment 472 Fig. 10.5. Concentrations of PCB and DDT (ng g-1 ww) in pike in the Bothnian Bay, Archipel- ago Sea and Gulf of Finland from 1971 to 1997.

Areal differences are small, but indicate est concentrations. The dominating higher concentrations in the eastern PCB congeners have been 153 and 138 Gulf of Finland. (IUPAC). The lowest congeners of PCB The long-term monitoring data by were the less chlorinated 28, 31 and 51. the Finnish Environment Institute DDE dominated in the total DDTs. The show that PCB and DDT concentra- pike studied were about 5–7 years old tions in pike (Esox lucius) in the Both- and their total weight usually ranged nian Bay, the Archipelago Sea and the from 800 to1200 g. A comparison of the Gulf of Finland were clearly lower in PCB and DDT concentrations in pike the 1990s compared to the 1970s or the and Baltic herring on a fat weight ba- 1980s and at a relatively constant level sis shows no difference. (PCB less than 15 ng g-1 ww and DDT -1 less than 10 ng g ww, Fig. 10.5). Sig- Dioxins and furans nificant areal differences were not found either in PCB or in DDT concen- Clearly older (age 4–9 years) Baltic her- trations from different sea areas. Con- ring was monitored by the Finnish En- centrations were only slightly higher in vironment Institute for PCDD and the Gulf of Finland than in the Archi- PCDF concentrations in muscle. Con- pelago Sea or in the Bothnian Bay. The centrations ranged from 0.3 to 3.6 pg g-1

latest results from 1997 show the low- ww calculated as ITEQ (Fig. 10.6). Sim- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 101 Fig. 10.6. Concentrations polychlorinated dioxins (PCDD) and furans (PCDF) (pg g-1 ITEQ ww) in Baltic herring in eight coastal areas from 1990 to 1999.

ilarly to PCB, concentrations were accurate estimate for human exposure. highest in the eastern Gulf of Finland In the age classes greater than eight (Hamina-Virolahti). Generally higher years, the increase in both PCDD/F and levels were measured in 1993–1996 PCB concentrations is significant. In compared to 1990, and at the Kuivanie- old fish (12–16 years) PCDD/F concen- mi station in the NW Bothnian Bay trations as high as 15–20 ITEQ pg g-1 with most frequent data a clear increas- ww and PCB 200 ng g-1 ww were meas- ing trend was observed (Figs. 10.2, ured by Vartiainen et al. (1997). Simi- 10.6). Concentrations were at the same larly, Verta et al. (1999c) reported a con- level as in Baltic herring of similar age centration of 15 pg g-1 ITEQ (ww) in a in the Baltic Proper (HELCOM 1993). homogenized Baltic herring sample The concentrations of PCDD/Fs from the eastern Gulf of Finland in 1996 and PCBs tend to increase in the mus- consisting of age classes 5–10 years. cle of Baltic herring with age (Vartiai- Korhonen et al. (1999) reported nen et al. 1997, HELCOM 1993). Un- concentrations from 7 to 8 pg g-1 (ww) like HELCOM monitoring Vartiainen ITEQ in Baltic salmon (Salmo salar) in et al. used unskinned fish filet, which the eastern Gulf of Finland. These con- gives a notably higher PCDD/F and centrations are in agreement with those

PCB concentrations enabling a more reported by Vuorinen et al. (1993) and ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

102 ○○○○○○○○○○○○○ The Finnish Environment 472 Vartiainen et al. (1997). The most dom- bleached pulp effluents and accumu- inant congeners were 2,3,4,7,8-PCDF late in the bile. Very low amounts were and 1,2,3,7,8-PCDD in salmon. In all observed in the fishes studied near other species the dominating congener Kemi. The levels of 345-TCG (3,4,6- was 2,3,7,8-TCDD. trichloroguaiachol) were 1–6 ng g-1 fw Perch (Perca fluviatilis), pike, bream and of 456-TCG below 1 ng g-1. These (Abramis brama), burbot (Lota lota) and concentrations are very low compared pike-perch (Stizostedion lucioperca) with up to much as 50 000 ng g-1 ww show clearly lower concentrations of 345-TCG found in the bile of perch PCDD/Fs than in Baltic herring; less dwelling 2 km from Norrsundet, a than 1 pg g-1 ww ITEQ, (Korhonen et large mill with conventional chlorine al. 1999). The concentrations of PCDDs bleaching, in the 1980s (Södergren and PCDFs in pike (length 50–60 cm 1989). and age 6–8 years) muscle were less The M74 syndrome appears as than 0.5 ITEQ pg g-1 ww in the begin- yolk-sack mortality and causes high ning of the 1990s. Only in 1992 in Ah- mortalities in salmon returning to Finn- venkoskenlahti Bay did the concentra- ish rivers. Yolk-sac mortality in salm- tion almost exceed 1 ITEQ pg g-1 ww. on has been about 70% in the river Si- When comparing the concentrations mojoki and less than 30% in the river on wet weight basis, the concentrations Kymijoki in the 1990s (Vuorinen et al. were about 10 times higher in Baltic 1993, 1997). Simultaneously with the herring than in pike. This is due to the mortality increase, the concentrations lipid content in pike (about 0.4%) be- of PCDD/Fs and expecially coplanar ing about ten times lower than in Bal- PCBs increased in salmon in the early tic herring (about 5%), while the con- 1990s as compared to the end of the centrations of dioxins in lipid were at 1980s. It is not yet clear whether the the same level. environmental pollutants or other rea- The Nordic Council of Ministers sons (carotenoids, thiamine, changes in recommended a Tolerable Daily Intake the abundance of important prey spe- (TDI) of 35 TEQ pg kg-1 body weight/ cies) are responsible for the yolk-sac week. According to these recommen- mortality of salmon. It has been hy- dations an individual weighing 70 kg pothesized, however, that due to the could have a daily consumption of about diminished growth rate of both sprat 350 g fish muscle with a PCDD/F con- and herring during the 1990s the salm- centration of 1 ITEQ pg g-1 ww. If old on has changed its diet to older prey Baltic herring or salmon were used, with higher PCDD/F concentrations, with PCDD/F concentrations of 10–20 which may have precipitated the M74 pg g-1 (ITEQ) and equal PCB concen- syndrome outbreak (Keinänen et al. trations (ITEQ) the maximum daily 2000). consumption should be 40 times low- Developmental disorders in the er (less than 10 g fish muscle) in order gonads of burbot and to a smaller ex- to remain below the guideline. tent in other fish species have been re- Chlorophenols originating from ported along the northern coast of the pulp mill were determined from pike Bothnian Bay. The fish in this area have and roach in the sea area off Kotka been exposed to a large number of (Heitto and Anttila-Huhtinen 1995). chemicals especially from pulp mills. The concentrations in pike varied from No detailed explanation is available for 125 to 205 ng g-1 fw and in roach from spawning incapacity and no clear 55 to 70 ng g-1 ww. Concentrations of cause/effect relationship between pol- trichloroguaiachols in the bile of perch lution and reproduction disorders has were studied in Kemi. These bioaccu- been found (Pulliainen et al. 1999).

mulating compounds are specific for ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 103 10.3 Oil and other are not fully comparable, the area with oil contamination was somewhat larg- contaminants from the er in 1987 than twelve years earlier. petrochemical industry During 1990s no major change in sediment oil concentrations occurred, with The sea area off Porvoo is loaded by clearly (10–100-fold) concentrations effluents from an industrial complex near the outlet of the cooling water outside Sköldvik. The complex consists compared to other stations. of an oil refinery and petrochemical Concentrations of chlorinated hy- plants, the products of which include drocarbons and phthalates in sedi- phthalates, styrene and PVCs. The ments have been measured since 1978. waste waters are treated by physio- The concentrations of chlorinated hy- chemical and biological methods. The drocarbons and 1,2-dichloroethane and waste waters from the petrochemical DOP (dioctylphtalate) have usually industry complex contain oil, sulphides, been below the detection limits, exept mercaptans, cyanide, hydrocarbons, for the sediments closest to the outlet. phthalates, phenols and heavy metals. Clearly highest phthalate concentra- Oil, phenols, chlorinated hydro- tions (up to 520 mg kg-1 dw) were carbons and phthalates are monitored found at this station, but also occasion- in water samples from areas close to ally at other nearby stations during re- the waste water effluent sites. Oil concent years. Data from most stations re- centrations in water samples have de- veal greatly increased concentrations creased considerably since the 1970s, during the late 1990s. when concentrations of more than 1000 mg l-1 were not uncommon. Generally, concentrations in the 1980s and 1990s 10.3.2 Fish have been under the detectable limit of 100 mg l-1. DOP concentrations in wa- Nakari (1992) studied metabolic chang- ter have also usually been low (<2–10 es and accumulation of pollutants in mg l-1). Vinylchloride has not been de- caged and wild fish in the sea area off tected and dichloroethane was detect- Sköldvik in 1990 and 1991. The physi- ed in concentrations of 0.05–0.15 mg l-1 ological status of two-year-old salmon in 1987. caged for 2 and 4 weeks near the outlet changed most compared to the control (Pellinki). The pollutants analysed 10.3.1 Sediment were aliphatic and polyaromatic hydrocarbons, phthalates, volatile chlo- The accumulation of oil in sediment rinated hydrocarbons, chlorophenols has been monitored regularly since and resin acids. The physiologial 1974 in the Porvoo area. The highest changes observed were in the water- oil concentrations were detected out- and ion regulation of fish, as well as in side the cooling water outlet. The oil their enzyme, lipid and hormonal me- concentration of the cooling water out- tabolism. Rather high amounts of vol- let site has decreased considerably dur- atile chlorinated hydrocarbons and ing the past 20 years but is still high. phthalates were found in caged fish The oil concentration at Illvarden fluc- (18–37 mg g-1 and 1.5–6.3 mg g-1, respec- tuates considerably (Talsi 1987). tively) in areas close to the petrochem- Villa (1989) constructed a map of ical factories. In free-living fish (pike), the areas contaminated with oil in 1987 concentrations were not different in compared to the situation in 1975. Al- areas near the factories compared with

though the analytical methods for oil the reference areas. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

104 ○○○○○○○○○○○○○ The Finnish Environment 472 General classification

of coastal water quality

○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○ 11

Sari Mitikka

Deterioration of water quality due to ters, this type of classification has been eutrophication, hazardous substances carried out nationwide in the begin- or hygienic bacteria is a common phe- ning of the 1980s (National Board of nomenon both in fresh and brackish Waters 1983), in the middle of the 1980s waters. For the general characterization (Vuoristo 1991) and in the middle of the of the quality of waters an index is 1990s (Antikainen et al. 2000). In addi- needed, which takes into account these tion, classification for some coastal re- various aspects of water quality. The gions has been reported for the begin- general classification applied in Fin- ning of 1990s (e.g. Puomio and Braun- land (National Board of Waters and the schweiler 1993, Ferin-Westerholm 1994). Environment 1988, Heinonen and However, comparison of the classifica- Herve 1987, Vuoristo 1998) divides tions made for those four periods is waters into five classes. Two approach- difficult, because the criteria have been es are in use to produce the general changed twice. First, in the beginning classification. First, the classes are de- of the 1980s two crucial variables, chlo- termined by a counting procedure rophyll a and total phosphorus, were based on three separate classification not yet included. Second, the bounda- criteria describing the suitability of ry values of these two variables (Table waters for water supply, fishing and 11.1) were lowered for sea waters com- recreational activities. Second, the con- pared with fresh waters in the latest centrations of relevant water quality classification (Antikainen et al. 2000). variables are compared with bounda- The new boundary values are consid- ry values which reflect the overall suit- ered to produce results which are in ability of waters for the above modes better agreement with the general con- of use. These variables include oxygen, ception of the state of the Baltic Sea. turbidity, chlorophyll a, total phospho- The latest nationwide classifica- rus, colour, transparency, toxic com- tion of the Finnish surface waters was pounds and algal blooms. In uncertain based on the data from the years 1994– situations, extra support can be found 1997, variables listed in Table 11.1 and by examining the criteria of the three verbal descriptions in Table 11.2. Ac- more specific classifications. The five cording to this study, ca. 88 % of the classes of the general index also have sea area had excellent or good water a verbal description to help in separat- quality, whereas only one percent was ing them from each other. As brackish passable or poor (Fig. 11.1). Eutrophi- coastal waters and sea areas are not cation had caused the quality of sea used for water supply, their general waters to deteriorate mainly in the Gulf index is decided by the second ap- of Finland and in the Archipelago Sea. proach. In general, excellent and good classes In Finland, water quality classifi- were located in the open sea. An ex- cation has been used for reporting the ception was the eastern Gulf of Fin- state of surface waters in national, re- land, where water quality was classi-

gional and local levels. In coastal wa- fied as only satisfactory. This was main- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 105 Figure 11.1. General classification of Finnish coastal waters based on water quality data from the years 1994–1997

(Antikainen et al. 2000). ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

106 ○○○○○○○○○○○○○ The Finnish Environment 472 ly due to eutrophication caused by and furans) that when using old Baltic wastewaters of St. Petersburg (Russia) herring or salmon as food, the maxi- and loading by the River Neva mum daily consumption should be less (Pitkänen 1994, Fig. 6.1). Loading from than 10 g fish muscle in order to remain Finnish rivers, which were mainly clas- below the Nordic guideline (Nordisk sified as passable, also decreased the dioxinriskbedömning 1988). In the quality of coastal waters. The effect of classification this could not be taken direct loading from municipalities and into account, because the data was industry could also be seen. Coastal sparse. Oil has been detected off an iron waters were classified as poor or pass- smelter near Hanko and this has de- able off the large municipalities, such creased the usability of water (Puomio as Hamina, Kotka, Porvoo, Helsinki, et al. 1999). Turku, Pori, Vaasa, Kokkola, Oulu and The general classification of wa- Kemi. In the Archipelago Sea, waters ter quality should have more exact around large fish farms were clearly boundary limits for harmful substanc- more eutrophic than neighbouring ar- es in water, fish and sediment. In ad- eas, but this could not be seen in the dition, it does not consider the state of scale of the national map. the whole aquatic environment, in- Increased numbers of hygienic cluding community structure of organ- indicator bacteria were noticed e.g. in isms. Furthermore, monitoring data – the sea area to which wastewaters of especially data on topical harmful sub- Helsinki are conducted (Puomio et al. stances – should be more numerous in 1999). Water quality of the rivers in order to provide more accurate classi- south and southwest Finland is often fication. Classification criteria are cur- decreased by high numbers of hygien- rently being developed under the wa- ic indicator bacteria (Niemi et al. 1997) ter framework directive of the Europe- and the effect of this could be seen in an Community (1997/0067/COD). First, some inner bays (e.g. Halikonlahti, coastal waters should be discriminat- Vanhankaupunginselkä). Decreased ed into different types to ensure that oxygen content in water worsened the type-specific biological reference con- class e.g in the Pohjanpitäjänlahti Bay, ditions can be reliably derived. Second, off Tammisaari and in the Sipoonlahti waters should be divided into five Bay (Puomio et al. 1999). Moreover, classes by comparing their ecological anoxic sediments and mortality of bot- quality with the reference conditions. tom fauna off Pyhtää-Kotka-Hamina The most remarkable difference (easternmost Gulf of Finland) affected between the recent classification and the assessment of water quality there. that demanded by the water frame- Acidity caused fish kills in 1996 espe- work directive will be the crucial role cially near the outlet of the Kyrönjoki, of biological elements, such as phyto- a river with a catchment dominated by plankton, macro algae, benthic inver- acid sulphate soils originating from the tebrate fauna and fish. The monitoring sediment of the former Littorina Sea. of these elements should be organized Mercury concentrations in the with a frequency of every three years muscle of predatory fish, such as pike, and for phytoplankton every six were below 1 mg kg-1, which is the months. Physical and chemical varia- maximum level for human consump- bles should be monitored at three tion (see also section 10.2.3.) and thus month intervals and some priority haz- did not have an influence on the allo- ardous substances even monthly. These cation of class. Classification criteria do demands for monitoring with empha- not give exact boundary values e.g. to sis on biological variables would most organic chlorine substances. It has been probably lead to reorganization of the

calculated (see section 10.3.3. Dioxins whole coastal monitoring in future. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 107 Table 11.1. Class boundaries of variables used in general classification of water quality (National Board of Waters and the Environment 1988, Vuoristo 1998, Antikainen et al. 2000). Variable I II III IV V Excellent Good Satisfactory Passable Poor Chlorophyll a, mg/l Fresh water <4 <10 <20 20–50 >50 Baltic Sea <2 2–4 4–12 12–30 >30 Total P, mg/l Fresh water <12 <30 <50 50–100 >100 Baltic Sea <12 13–20 20–40 40–80 >80 Transparency, m > 2.5 1–2.5 <1 Turbidity, FTU <1.5 >1.5 Colour mg Pt/l <50 50–100 <150 >150 >150 (<200)*

O2, % 80–110 80–110 70–120 40–150 serious problems in surface water Oxygen depletion in hypolimnion no no occasionally frequently common Faecal indicator <10 <50 <100 <1000 >1000 bacteria, CFU/100 ml Hg, mg/kg in carnivorous fish >1 As, Cr, Pb, mg/l <50 >50 Hg, mg/l <2 >2 Cd, mg/l <5 >5 Total cyanide, mg/l <50 >50 Algal blooms no occasionally frequently common abundant Off-flavours in fish common common * humic waters in their natural state

Table 11.2. Criteria for the general water quality classification in Finland (National Board of Waters and the Environment 1988,Vuoristo 1998, Antikainen et al. 2000) Class I (Excellent) The watercourse is in natural condition, usually oligotrophic, clear or with some humus. No algal blooms preventing the use of water. Highly suitable for all modes of use.

Class II (Good) The watercourse is in near-natural condition, slightly eutrophic or with moderate humus content. Local algal blooms might occur occasionally. Water is still suitable for all modes of use.

Class III (Satisfactory) The watercourse is slightly affected by wastewaters, non-point loading or other changing activity, or it is appreciably eutrophic due to natural causes, or highly coloured with humus. Algal blooms may occur repeatedly. Concentrations of harmful substances in water, sediment and organisms may be slightly increased compared with natural levels. The watercourse is usually satisfactory for most modes of uses.

Class IV (Passable) The watercourse is strongly affected by waste waters, non-point loading or other changing activity. Algal blooms are common and may restrict the use of water for long periods. Concentrations of harmful substances in water, sediment and organisms can be clearly higher compared with natural levels. Acidity may occasionally cause fish kills in waters in catchments dominated by acid sulphate soils originating from the sediment of the former Littorina Sea. Water is suitable only for modes of use having few water quality requirements.

Class V (Poor) The watercourse is extensively polluted by wastewaters, non-point loading or other changing activity. Algal blooms are very common and abundant, restricting the use of water often for long periods. Oxygen condition may also be weak due to eutrophication. Concentrations of harmful substances in water, sediment and organisms may be at level causing a clear risk associated with the use of either water or organisms. Acidity repeatedly causes fish kills in waters on catchments dominated

by acid sulphate soils originating from the sediment of the former Littorina Sea. Poorly suited to any form of water use. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

108 ○○○○○○○○○○○○○ The Finnish Environment 472 Summary and conclusions

The aim of this report is to assess the northern rivers to the Bothnian Bay. state of Finnish coastal waters and However, as the loading is expressed changes in it during the 1990s. Load- as total nutrients, it does not directly ing and concentrations of nutrients and describe the biologically available and harmful substances have been re- eutrophying share of the load. viewed in different coastal areas. Eu- The load of phosphorus has de- trophication has been described by creased by ca. 16% and the load of ni- means of biomass and surface accumu- trogen ca. 10% from the level in the late lations (blooms) of phytoplankton. The 1980s. In particular, the reduction in the state of the coastal zone has been as- municipal and industrial load of P was sessed as changes in phytobenthos and significant. By contrast, changes in dif- zoobenthos. The report is mainly based fuce loading were slight. The decline on the coastal monitoring data pro- in the total load of N since the late duced by the Finnish Environment In- 1980s was explained by the smaller stitute. The physical and chemical water flow in the 1990s because the monitoring data in open sea areas orig- point-source loading of N actually inated from the Finnish Institute of slightly increased during that period. Marine Research. The section on fish The decline in the load of P was main- catches was delivered by the Finnish ly due to water protection measures in Game and Fisheries Research Institute. industry and municipalities. Numerous scientific arcticles and re- Targets set in the Ministrial Dec- ports were evaluated to assess the laration of Baltic countries in 1988 for changes in phytobenthos because mon- decreasing industrial and municipal itoring data for phytobenthos was not loading of P to the Baltic Sea were available. Additionally, local pollution achieved in the 1990s. On the other control studies were utilized in order hand, the load of N from agriculture, to obtain additional information on municipalities and industry did not zoobenthos and harmful substances in significantly decrease. A new national polluted water areas. target has been set to decrease the load of nutrients by about 50% from all sources of nutrient loading by the year Loading 2005 compared to the level of 1990– During the 1990s, Finnish coastal wa- 1995. The decrease in the point-source ters received annually on average 4 090 load of organic matter (BOD7) by more t of P and 74 000 t of N from or via the than 70% since the mid 1980s was due Finnish territory, corresponding to ap- to improved purification of waste wa- proximately 10% of the total loads of ters in the wood-processing industy. nutrients to the Baltic Sea. In the Finn- In addition to eutrophication, con- ish catchment, agriculture was the tamination by metals and other harm- main anthropogenic source of P and N ful substances is also a matter of con- loading, accounting for one third of the cern in many coastal water areas. The total fluxes of nutrients. The munici- load of heavy metals carried via rivers pal load of N was the second largest to the coastal waters spans several or- and atmospheric deposition the third ders of magnitude compared to point- largest source of N load. Regarding the source loading due to natural leaching load of P, forestry was the second larg- from soil. Therefore, the effects of wa- est and scattered dwellings the third ter protection measures on the total largest source. The majority of the load load of heavy metals remain relatively

of forestry was carried via the large small. In local scale the reduction in the ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 109 industrial and municipal loads of the Gulf, where nutrient reserves in heavy metals are important as they bottom relatively easily reach the pro- have a contribution to the state of the ductive surface layer due to the lack of biota. Nevertheless, the point-source halocline. In the eastern Gulf of Fin- loads of metals have considerably de- land, internal loading of nutrients were creased since the 1970s and 1980s. Ad- accelerated in the mid 1990s due to ditionally, the hot spots specified by strengthened of stratification and in- HELCOM in the Helsinki Convention complete wintertime mixing. in 1992 have decreased throughout the Nutrient conditions in the Gulf of whole Baltic catchment. In Finland, Bothnia differ considerably from those metal industry discharging to the Both- in the Gulf of Finland. The Gulf of nian Sea via the river Kokemäenjoki is Bothnia is sheltered from the majority still left in the list due to its considera- of the nutrient-rich deep waters by a ble load. ridge, shaped by several underwater thresholds and the Archipelago Sea. Therefore, only small water volumes from the eutrophied Baltic water below Nutrient conditions and the halocline enter to the Gulf of Both- trophic status nia. Additionally, due to the smaller Nitrogen and phosphorus are key ele- external nutrient loading and the lack ments for primary producers (phyto- of areas receiving considerable internal plankton, macroalgae, higher water loading, the amount of phytoplankton plants). Additionally, silicate is an im- in the Gulf of Bothnia is clearly small- portant element for diatoms. In the er than in the Gulf of Finland. In the coastal waters of the Gulf of Finland, Archipelago Sea, the general trophic the Archipelago Sea and the Bothnian status in summertime is lower than in Sea, algal production is mainly limit- the western Gulf of Finland. ed by nitrogen or by both nitrogen and Most of the Finnish coastal waters phosphorus. By contrast, production in are eutrophied compared to open sea the Bohnian Bay is clearly phosphorus areas. The eutrophied zone (more than limited. However, in all environments 5 mg chl a m-3) along the coast of the the availability of phosphorus controls Gulf of Finland and the Archipelago blue-green algae which are cabable of Sea is explained by the even distribu- fixing atmospheric nitrogen dissolved tion of riverine nutrient load directed in water. to the coastal areas. In the Gulf of Both- Eutrophication is the main prob- nia, eutrophied coastal areas were lim- lem in the Gulf of Finland, where the ited to estuaries or archipelagos off nutrient load per unit water area is 2–3 greater cities. Regarding the open sea, times greater than in the whole Baltic only the eastern Gulf of Finland is Sea. The sensitivity of the Gulf to eu- clearly eutrophied due to the consid- trophication is increased by many fac- erable load of nutrients from the River tors. The Gulf of Finland is a direct ex- Neva and the St. Petersburg region, tension of the Baltic Proper, being in- and also due to its current and mixing fluenced by the deep water of the Bal- conditions. tic Proper. Additionally, it is affected by Changes in trophic status since considerable nutrient load from land the 1970s exhibit two opposite direc- areas, mainly originating from the Riv- tions. The state of some clearly eutro- er Neva and St. Petersburg region. phied areas off greater cities (e.g. the Nutrient supplies become available for Helsinki-Espoo region and Oulu) show phytoplankton through upwellings improvement due to the decrease in and strong mixing events in late au- municipal and industrial nutrient load- tumn and winter. In generel, water ing. Especially phosphorus concentra- mixing does not effectively reach the tions in heavily loaded areas have de-

bottom, except in the eastern parts of creased due to water protection meas- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

110 ○○○○○○○○○○○○○ The Finnish Environment 472 ures aimed at reducing point-source ton amounts levelled out in the late loading. However, the total surface 1990s in keeping with phosphorus con- area of the coastal waters defined as centrations, which due to extensive oxy- eutrophied (more than 5 mg chl a m-3) gen deficit were elevated in the middle of has increased during the 1980s. The the decade. The dominance of blue-green situation in the 1990s has not essential- algae has increased since the late 1980s. ly changed compared to that in the The nutrient ratios and hydrographical 1980s. conditions determined which of the During the 1980s, the border of blue-green algae, Planktothrix agardhii slightly eutrophied areas moved west- or N2-fixing Aphanizomenon sp., gained wards in the Gulf of Finland, in the dominance. P. agardhii has mainly domi- outer Archipelago Sea and in the Both- nated in summers when nutrient rich nian Bay. The reason for this are chang- waters have extended as far as the east- es in N loading and changes in nutri- ernmost Finnish archipelago. ent concentrations in the open Baltic In the outer archipelago off Hel- Sea. The increase in N concentrations sinki, the increase in nutrient concen- in the open Gulf of Finland was also trations since purified waste waters observed in the coastal waters during started to be conducted to open sea was the 1970s and 1980s. N loading from not reflected in total phytoplankton the coast continuously increased as a biomasses. However, the increase in result of increased nutrient leaching the inorganic N:P ratio favoured flour- and use of fertilizers. Additionally, in- ishing of the blue-green algal order tensified fish-farming contributed to Chroococcales at the expense of Apha- the development of eutrophication in nizomenon sp., which in these altered the Archipelago Sea in the late 1980s. conditions could not take advantage of

Phosphorus concentrations began its N2-fixing capability. Similarily, the to increase strongly in the Gulf of Fin- decline in phosphorus concentrations land in the middle of the 1990s due to in inner bays resulted in the dominance the acceleration of internal loading, of non-N2-fixing blue-green algae. especially in the eastern part of the In the Archipelago Sea, the in- Gulf. Consequently, the decrease in the crease in total phytoplankton biomass- ratio of inorganic N:P led to mass oc- es in the 1990s as a response to the in- currences of N2-fixing blue-green algae. crease in the concentrations of P can However, the increase in phosphorus partly be explained by internal loading concentrations ceased at the end of the and nutrient fluxies from the Gulf of 1990s. The decreasing trend of N con- Finland. In recent years, the decrease centrations in the coastal and open in the N/P ratio and the increase in N Gulf of Finland was possibly due to the limitation has probably contributed to decline in the load of N by 30% com- the dominance of blue-green algae. pered to the level in the late 1980s. Eutrophication in the Gulf of Fin- land and the Archipelago Sea has been reflected as increasing extent and intensity of algal accumulations in late Phytoplankton and blue-green summer. Mass occurrences of blue- algae green algae have also occasionally been The development of eutrophication in recorded in late autumn or early win- the Gulf of Finland and the Archipela- ter. The accumulations are rare in the go Sea was manifested as an increase Bothnian Bay. In the accumulations, in late summer phytoplankton biomass Aphanizomenon sp. and the occassion- and as changes in species composition. ally toxic Nodularia spumigena are the In the eastern Gulf of Finland, the in- most common blue-green algal species, creasing trend of phytoplankton gen- both of which are capable of fixing at- erally followed the trend of nutrients. mospheric nitrogen. The accumula-

However, the increase in phytoplank- tions are often enhanced by upwellings ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 111 of near-bottom waters, carrying abun- are probably the main factor inducing dant amounts of phosphorus up to the hypoxia above the halocline in the ar- surface layer. In 1997, the accumula- chipelago area in the northern Baltic tions were the most extensive and pro- Sea. longed ever recorded. This phenome- Fucus vesiculosus is the only large non was attributed not only to calm perennial seaweed which is wide- and warm weather conditions but also spread in the Finnish coastal areas and to elevated concentrations of surface as such it forms the habitat for e.g. the phosphorus. In the summers 1998- hardbottom macrofauna. The distribu- 2000, accumulations were also record- tion area of F. vesiculosus reaches north ed in the inner Archipelago Sea. Nitro- up to the Quark and in the eastern part gen limitation explains why the accu- of the Gulf of Finland extends to Viro- mulations of blue-green algae are lahti. In sheltered shores it was found mainly formed in offshore waters. to grow on stones and could be restrict- From there they can be driven to the ed by soft sediments. General deterio- coast. The blue-green algae Microcystis ration of the F. vesiculosus belt is of great and Planktothrix, which form accumu- concern because it is a key species in lations near the coast and in the east- the Baltic Sea ecosystem. An extensive ernmost Gulf of Finland, also require decline of F. vesiculosus stands occurred inorganic N and suitable weather con- in the southern and SW coasts of Fin- ditions in addition to phosphorus. land during the late 1970s. Especially the F. vesiculosus belt disappeared al- Phytobenthos most completely from open archipelago shores and the abundance of F. ve- When eutrophication increases, sedi- siculosus also decreased drastically mentation and algal species favouring along the open shores. The first signs eutrophication occupy a larger area. of recovery were observed in the early Along the Finnish coast, changes such 1980s in the SW coast of Finland e.g. in as decreased occurrence of perennial the Tvärminne archipelago. In the Ar- red and brown algae, increased occur- chipelago Sea, F. vesiculosus had also rence of fast-growing filamentous al- completely vanished from many local- gae and drifting algal mats causing ities in the early 1980s. By the late 1980s anoxia have occurred. Furthermore, and the early 1990s it had partly recol- the upward movement of the algal onised its former habitats, but the de- belts due to increased sedimentation, cline had continued in some parts of overgrowth by epiphytic algae and in- the archipelago. Earlier, F. vesiculosus creased shading by plankton have was recorded to grow at a depth of 10 widely been documented. m in the Tvärminne archipelago but in Drifting macroalgae have been the 1990s its maximum growth depth encountered in the 1990s in the Archi- was about 5 to 6 metres with an opti- pelago Sea and the Åland Sea and also mum of 2–3 metres. In the Archipela- in smaller amounts in the eastern Gulf go Sea, the continuous belt of F. vesicu- of Finland. When the filamentous mac- losus nowadays colonizes only a zone roalgae are detached from the rocky between depths of 1.0 to 4.0 metres, al- shores they are transported to the sub- though individual plants may be found littoral, where they may form loosely- down to a depth of 7–8 metres. ing drift mats. As a result, the natural littoral vegetation can be replaced and Alien species the bottom fauna can be altered by an algal mat covering the available sub- Introduction of alien species was re- strata. It has been shown that with in- cently recognised as a threat to the Bal- creasing eutrophication drifting algal tic ecosystem. Most of them have en- mats increase, affecting the entire coast- tered with ballast water or attached to

al food web. At present these algal mats the hulls of ships. Five alien species ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

112 ○○○○○○○○○○○○○ The Finnish Environment 472 recorded in Finnish coastal waters in be explained by weakening oxygen the 1990s have become established. The conditions in bottoms due to increased polychaete Marenzelleria viridis living in production of organic matter, and a bottom sediment, originates from the typical phenomenon to extensive are- northern America, whereas the bivalve as of the Gulf of Finland has been an- Dreissena polymorpha, the mysid shrimp oxic bottoms with no fauna due to both Hemimysis anomala and the cladoceran internal and external loading. Cercopagis pengoi are of Black Sea and Long-term monitoring results of Caspian Sea origin. Cercopagis has the macrozoobenthos communities of formed mass occurrences and caused relatively clean sea areas are available economic damage by sliming fishing only from one area, east of the Hanko gear and nets. The sensitivity of the Penisula. The most remarkable change Baltic Sea to these newcomers is main- on that bottom was the change in dom- ly a consequence of the low number of inance of the two main species, Mono- different species, which is typical to poreia affinis and Macoma balthica. The this relatively young brackish water strong dominance of Monoporeia in the region. There is a potential risk that al- 1980s turned to an even stronger dom- ien species may change the existing inance of Macoma in the 1990s. This, ecosystem and food webs or cause eco- like changes of some other species as nomic harm e.g. by disturbing fishing well, could be explained by the general or by blocking water cooling systems. eutrophication of coastal waters. How- ever, the recent species composition Zoobenthos resembles that recorded in the area already in the 1920s, indicating that oth- Changes in the state of bottom fauna er factors, such as intra- and interspe- have occurred in many coastal area af- cific regulation, also strongly affect the ter the late 1980s. Off the coast of load- development of bottom communities. ed areas these changes exhibited considerable regional differences. The decrease in the loading of organic matter Fish stocks and phosphorus improved the state of bottoms in the innermost parts of sev- Eutrophication generally affects fish eral heavily loaded areas. On the other stocks by increasing the abundance hand, off several other coastal areas, and biomass of fish, mainly due to an e.g. in the middle Gulf of Finland, the increase in the supply of their food. It bottoms have deteriorated despite the also changes the composition of fish decrease in point-source loading. These species towards the dominance of differences between different areas roach (Rutilus rutilus), improves the may arise from several factors, due to growth of some species, and increases the fact that waste water effects depend young and small fishs. On the other not only on the amount and the char- hand, some species also suffers from acter of loading, but also on coastal eutrophication. For example the disap- morphometry, bottom quality and wa- pearance of Fucus communities in ex- ter exchange conditions. tensive bottom areas due to higher tur- The bottom state of the outer ar- bidity has weakened the living condi- chipelago areas have hardly changed tions for e.g. perch (Perca fluviatilis). in the Gulf of Bothnia, but have gone Many fish also avoid waters with low deteriorated in the Archipelago Sea, oxygen content. The direct harmful ef- and especially in the Gulf of Finland fects of eutrophication on commercial during the 1990s. This is manifested as and recreational fisheries are manifest- e.g. decreasing abundances of Mono- ed as fouling or sliming of gear and nets, poreia affinis and increasing abundanc- and off-flavours or -odours in fish. es of oligochaets and chironomid lar- Salinity also affects the composi-

vae. The deterioration of the fauna can tion, abundance and distribution of ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 113 fish species. The salinity of the Baltic sions of these compounds have de- Sea has decreased due to the absence creased due to water protection meas- of major inflow events via the Danish ures. High concentrations were also straits during the 1980s and 1990s, with measured in biota. However, concen- the exception of the most recent, moder- trations of PCB and DDT have declined ately strong inflow in 1993. The slight in Baltic biota since the 1970s. In Baltic decline in salinity in the Gulf of Finland herring this decline has slowed during and the Archipelago Sea has indirectly the 1990s. been reflected e.g. in decreased growth The petrochemical industry is an of Baltic herring (Clupea harengus) due important source of oil compounds in to the decrease in its food item. Baltic Finnish coastal waters. In general, con- herring is the most important marine centrations in water have been below species for Finnish commercial fisheries. the detectation limit during the 1980s and 1990s. The highest oil contents in sediment were detected outside the Contamination of harmful cooling water outlets. In the vicinity of substances petrochemical factories concentrations Considerable amounts of heavy metals, in free-living fish did not differ from organic pollutants and other persistent normal levels. The harmfulness of oil harmful compounds from point- and compounds in biota is based on the fact diffuse sources have discharged into that in high concentrations they can the Finnish coastal waters. This is also cause physiological changes. evident on the basis of elevated concentrations in sediment and biota. Persist- ent hazardous compounds can become Classification of coastal water enriched in the food webs of members quality of the biota and cause changes in their On the basis of the general classifica- reproduction, growing and metabolism. tion of coastal water quality, nearly 90% The distributions of the heavy of the sea area was classified as good metals Pb, Cd and Hg in sediment or excellent, which shows that water- showed a decreasing trend from north courses are in natural or near-natural to south in the Gulf of Bothnia, and condition. Good and excellent water from east to west in the Gulf of Finland. classes covered open sea areas around Mercury concentrations were highest in Finland and extensive coastal areas in the Bothnian Bay and cadmium con- the Gulf of Bothnia. About 10% of the centrations in the Gulf of Finland. How- water area belonged to the satisfactory ever, the maximum concentrations class, situated along the coasts of the were far below the Baltic extremes. Gulf of Finland, the Archipelago Sea High contents of different metals in bi- and off loaded coastal areas in the Gulf ota were measured in the vicinity of of Bothnia. Only one percent of the industrial areas. Metal concentrations water area was classified as passable. in the Baltic mussel (Macoma balthica) The reason for these lower water class- did not differ significantly from back- es is mainly europhication, manifest- ground variation. Saduria entomon ed e.g. as elevated concentrations of showed a decline in the concentrations chlorophyll a, frequent algal accumu- of copper, cadmium and mercury. Mer- lations or low oxygen concentrations cury concentrations in fish in areas with in bottom layers. Additionally, hygienic high Hg pollution decreased consider- indicator bacteria weakened water ably during the 1960s and 1970s. quality in some inner bays, and elevat- Concentrations of organic polluted concentrations of harmful substanc- ants in sediment were elevated in the es such as Hg and organic chlorine sub- vicinities of woodprocessing and pet- stances off some industrial areas.

rochemical industries. However, emis- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

114 ○○○○○○○○○○○○○ The Finnish Environment 472 Yhteenveto

Suomen rannikkovesien tilaraportissa vaa suoraan rehevöitymisestä aiheut- arvioidaan rannikkovesien tilaa ja sen tavaa, biologisesti käyttökelpoista muutoksia 1990-luvulla. Tarkasteluun osuutta kuormituksesta. on otettu ravinnekuormituksen kehi- Fosforin kuormitus on pienenty- tys sekä ravinne- ja rehevyystasot ja nii- nyt 1980-luvun loppuun verrattuna den muutokset eri rannikkovesialueil- noin 16 % ja typen kuormitus noin la. Rehevöitymistä on kuvattu kas- 10 %. Erityisesti asutuksen ja teollisuu- viplanktonin biomassan ja kukintojen den fosforikuorma pienentyi merkittä- avulla. Rantavyöhykkeen tilaa on ar- västi. Sen sijaan hajakuormassa muu- vioitu kasvillisuudessa ja pohjaeläimis- tokset olivat vähäisiä. Typpivirtaami- tössä tapahtuneina muutoksina. Suo- en väheneminen selittyy pääasiassa sa- men ympäristökeskus on koonnut suu- dannan ja valumien pienenemisellä, rimman osan raportin aineistosta. Ra- mikä on heijastunut sekä luonnosta portti on laadittu valtakunnallisten että maa- ja metsätaloudesta peräisin seurantaohjelmien, velvoitetarkkailu- oleviin ravinnehuuhtoumiin. Kuiten- jen sekä rannikkovesien tilaa käsittele- kin 1990-luvulla myös typen vuotui- vien tutkimusten perusteella. Avome- nen kuorma pienentyi valtakunnalli- rialueen vedenlaatutiedot on saatu sesti noin 4 000 tonnia. Noin puolet täs- Merentutkimuslaitoksen seuranta-ai- tä vähenemästä johtuu pääkaupunki- nestosta. Kaloihin ja kalastukseen liit- seudulla vuonna 1998 aloitetusta te- tyvän osuuden on toimittanut Riista- hostetusta typenpoistosta ja toinen ja kalatalouden tutkimuslaitos. Velvoi- puoli teollisuuden päästöjen pienene- tetarkkailun aineistoa on hyödynnetty misestä. Itämeren valtioiden yhteisen arvioitaessa pohjaeläinten tilaa ja hai- Ministerijulkilausuman vuonna 1988 tallisten aineiden pitoisuuksia ja vai- asettama tavoite teollisuuden ja yhdys- kutuksia kuormitetuilla vesialueilla. kuntien fosforikuormituksen vähentä- miseksi onnistui. Sen sijaan maatalouden, asutuksen ja teollisuuden typpi- Kuormitus kuorma ei ole merkittävästi vähentynyt. Suomen rannikkovedet vastaanottivat Suomen kansallisen vesiensuojelun ta- valuma-alueeltaan keskimäärin noin voiteohjelman tavoitteena on kaikkien 4 090 tonnia fosforia ja 74 000 tonnia päästölähteiden ravinnekuormituksen typpeä vuodessa, mikä on noin 10 % vähentäminen noin 50 %:lla vuosien Itämereen päätyvästä ravinnekuor- 1990–1994 tasosta vuoteen 2005 men- masta. Maatalous on selvästi suurin nessä. yksittäinen typen ja fosforin kuormi- Raskasmetallien ja vahingollisten tuslähde. Rannikkovesiin joutuvasta aineiden aiheuttama saastuminen on typpikuormasta asutus on toiseksi suu- rehevöitymisen ohella huolenaihe rin ja järvialueilta peräisin oleva typ- useilla Suomen rannikkovesialueilla. pilaskeu-ma kolmanneksi suurin läh- Luonnonhuuhtouman vuoksi jokien de. Fosforikuormittajista metsätalous ja mukanaan kuljettamat raskasmetalli- haja-asutus ovat maatalouden jälkeen määrät ovat useita kertaluokkia suu- suurimmat kuormituslähteet. Arviolta rempia kuin mitä rannikkovesiin pää- 80 % metsätalouden kuormasta koh- tyy asutuksesta ja teollisuudesta. Siten distuu Perämereen siihen laskevien vesiensuojelutoimenpiteillä voidaan suurien jokien välityksellä. Raportissa verrattain vähän vaikuttaa raskasme- esitetyt luvut ovat kuitenkin kokonais- tallien kokonaispäästöihin. Tästä huo-

ravinnekuormia, eivätkä ne siten ku- limatta teollisuuden ja yhdyskuntien ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 115 raskasmetallien kuormitusta pienentä- lahdella ravinteiden sisäinen kuormi- mällä voidaan parantaa eliöiden elin- tus kiihtyi 1990-luvun puolivälissä. olosuhteita. Raskasmetallien pistemäi- Tämä johtui kerrostuneisuuden voi- nen kuormitus onkin vähentynyt mer- mistumisesta ja veden epätäydellises- kittävästi 1970- ja 1980-lukujen aikana. tä sekoittumisesta talvikausina. Itämeren suojelukomission Helsinki Pohjanlahti eroaa ravinneoloil- sopimuksessa vuonna 1992 määrittele- taan merkittävästi Suomenlahdesta. mät erityiskohteet (hot spots) ovat vä- Sitä suojaa Itämeren ravinteikkaalta hentyneet koko Itämeren alueelta. Suo- syvältä vedeltä Saaristomeren ja ve- men valuma-alueella sijaitsevista hai- denalaisten kynnysten muodostama tallisten aineiden kohteista on jäljellä harjanne, joiden vaikutuksesta vain Perämerta Kokemäenjoen kautta kuor- hyvin pieniä määriä Itämeren haloklii- mittava metalliteollisuus huomattavi- nin alapuolista, ravinteikasta vettä pää- en raskasmetallipäästöjensä vuoksi. see Pohjanlahdelle. Merialueen ulkoi- nen ravinnekuorma on lisäksi pienem- Ravinne- ja rehevyystila pi kuin Suomenlahden. Pohjanlahdel- la ei ole merkittäviä sisäisen kuormi- Typpi ja fosfori ovat tärkeimmät Itäme- tuksen alueita, joten avoimen Pohjan- ren rehevyystilaan vaikuttavat tekijät. lahden keskimääräinen kasviplankton- Suomenlahden, Saaristomeren ja Selkä- pitoisuus on kesällä selvästi pienempi meren rannikkovesissä levätuotanto on kuin Suomenlahdella. Saaristomeri pääosin joko typpi- tai sekä typpi- että muodostaa vaihettumisvyöhykkeen fosforirajoitteista. Perämeri puolestaan pohjoisen Itämeren ja Selkämeren vä- on levätuotannoltaan selkeästi fosfori- lillä, ja siellä yleinen rehevyystaso on rajoitteinen. Ensisijaisesti fosforin saa- kesällä vähän alempi kuin läntisellä tavuus säätelee kaikkialla niitä sinile- Suomenlahdella. välajeja, jotka kykenevät sitomaan il- Pääosa Suomen rannikkovesistä makehästä veteen liuennutta rajatonta on selvästi rehevöitynyt vastaaviin typpivarastoa. avomerialueisiin verrattuna. Tämä joh- Suomea ympäröivillä Itämeren tuu toisaalta rannikkovesiin joutuvas- osa-alueilla rehevöityminen on eden- ta ravinnekuormasta ja toisaalta ran- nyt pisimmälle Suomenlahdella, jonka nikkovesien mataluudesta sekä saari- vesipinta-alaan suhteutettu ravinne- en ja matalikkojen heikentämästä ve- kuorma on 2–3-kertainen koko Itäme- denvaihdosta avomeren kanssa. Selvim- reen verrattuna. Suomenlahden rehe- min rehevöityminen näkyy Suomenlah- vöitymisalttiutta lisää myöskin se, että den ja Saaristomeren kuormitetuilla se on Itämeren pääaltaan kynnyksetön saaristoalueilla, joissa yli 5 mg m-3 kes- jatke. Tämän vuoksi Itämeren pääal- kimääräinen kesän a-klorofyllin taso taan syvänteisiin kertyneet ravinneva- vallitsee lähes koko rannikon pituudel- rat pääsevät virtaamaan halokliinin ta. Yhtenäinen rehevöitynyt vyöhyke alapuolella esteettä Suomenlahdelle. selittyy rajoittuneiden sekoittumisolo- Tuottavaan pintakerrokseen ravinteet jen ohella jokien tuoman kuorman var- joutuvat kumpuamisten sekä erityises- sin tasaisella jakautumisella pitkin ran- ti myöhäissyksyn ja talven voimakkai- nikkoa. Pohjanlahden rannikkovesissä den sekoittumisten yhteydessä. Länti- 5 mg m-3 keskimääräinen a-klorofylli- sen ja keskisen Suomenlahden syvim- pitoisuus ylittyy paikoitellen. Avome- missä osissa sekoittuminen ei koskaan rialueilla keskimäärin 5 mg m-3 kesäai- yllä tehokkaana pohjaan saakka. Sen kainen a-klorofyllipitoisuus ylittyy sijaan itäisellä Suomenlahden sekoittu- vain itäisellä Suomenlahdella. Syynä misen estävä suolaisuuden harppaus- rehevöitymiseen ovat Nevan Pietarin kerros puuttuu ja pohjan ravinnevaro- mittava ravinnekuorma sekä Suomen- ja pääsee tuottavaan pintakerrokseen lahden virtaus- ja sekoittumisolot.

suhteellisen helposti. Itäisellä Suomen- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

116 ○○○○○○○○○○○○○ The Finnish Environment 472 Rannikkovesien ravinne- ja rehe- vastaava trendi on todettu itäisellä Suo- vyystilassa on 1970-luvulta lähtien val- menlahdella, lievempänä myös avoi- linnut kaksi vastakkaista suuntaa. Eräi- mella Suomenlahdella. Fosforipitoi- den aikaisemmin hyvin voimakkaasti suuden kasvu taittui 1990-luvun lo- rehevöityneiden alueiden (esim. Hel- pussa ja talvella 2000 Suomenlahden sinki-Espoo ja Oulu) tila on parantu- fosforipitoisuus oli palannut lähelle nut, kun asutuksen ja teollisuuden jä- 1990-luvun alkupuolen tasoa. Typen tevesien puhdistamista on tehostettu. laskeva trendi sekä Suomenlahden ran- Erityisesti kuormitettujen alueiden fos- nikkovesissä että avomerialueella foripitoisuus on laskenut, sillä piste- 1990-luvulla on mahdollisesti yhtey- kuorman fosforin vähentämistoimet dessä kuormituksen vähentymiseen ovat olleet tehokkaita. Kuitenkin rehe- noin 30%:lla 1980-lopun tasoon verrat- vöityneiden alueiden kokonaispinta- tuna. alassa tapahtui 1980-luvulla kasvua, jos mittapuuna pidetään alueita, joilla Kasviplankton ja sinilevät kesäisin ylittyy keskimäärin 5 mg m-3 a-klorofyllipitoisuus. 1990-luvulla ti- Myöhäiskesän kasviplanktonmäärän lanne ei ole oleellisesti muuttunut kasvu ja lajikoostumusmuutokset il- 1980-luvun loppuun verrattuna. mentävät lisääntyvää rehevöitymistä Myös lievästi rehevöityneiden Suomenlahdella ja Saaristomerellä. alueiden (3-5 mg m-3) pinta-ala lisään- Itäisellä Suomenlahdella kasviplankto- tyi 1980-luvulla sekä läntisellä Suo- nin määrän lisääntyminen on ollut sa- menlahdella, Saaristomerellä että Perä- mansuuntainen ravinnepitoisuuksien merellä siten, että alueet ovat paikoi- trendin kanssa. Kasviplanktonin mää- tellen levinneet rannikkovesistä avo- rän kasvu on tasaantunut 1990-luvun meren puolelle. Tilamuutosta voidaan jälkipuoliskolla, samoin fosforipitoi- selittää sekä avoimen Itämeren ravin- suudet, jotka olivat koholla vuosikym- nepitoisuusmuutoksilla että muutok- menen puolivälissä laaja-alaisen hap- silla typpikuormituksessa. Typen pitoi- pikadon seurauksena. Myös sinilevät suuden nousu 1970- ja 1980-luvulla ovat lisääntyneet 1980-luvun lopulta Suomenlahden avomerialueilla heijas- lähtien. Leväyhteisössä valtalajeina tui myös Suomenlahden rannikkove- ovat olleet Planktothrix agardhii ja ty- sissä, etenkin kun samaan aikaan myös pensitoja Aphanizomenon sp. Mm. epä- maalta tuleva typpikuormitus jatku- orgaanisen typen ja fosforin suhde sekä vasti kasvoi mm. valumien ja lannoit- vallitsevat hydrografiset olosuhteet teiden käytön lisääntymisen seurauk- vaikuttavat lajien asemaan leväyhtei- sena. Saaristomerellä rehevöitymiske- sössä. P. agardhii on monasti vallinnut hitykseen varsin ilmeisesti vaikutti silloin, kun Nevan ravinnepitoisia ve- muiden tekijöiden ohella kalankasva- siä on poikkeuksellisesti kesällä ulot- tuksen voimakas lisääntyminen 1980- tunut Suomen itäiseen saaristoon asti. luvun lopulla. Kasviplanktonin kokonaismäärät Suomenlahden fosforipitoisuus eivät ole lisääntyneet Helsingin ulko- alkoi 1990-luvun puolivälissä kohota saaristossa, vaikka puhdistetut jäteve- varsin voimakkaasti, mikä johtuu eri- siä alettiin 1980-luvun lopulla johtaa tyisesti itäisen Suomenlahden sisäisen ulkosaaristoon. Epäorgaanisen typen ja kuormituksen kiihtymisestä vuosi- fosforin suhteen kasvu on suosinut kymmenen puolivälin tienoilla. Ilma- Chroococcales -lahkon sinileviä. Aphani- kehän typpeä sitovien sinilevien mas- zomenon -lajit eivät muuttuneissa olo- saesiintymien intensiteetti lisääntyi suhteissa pystyneet hyötymään typen- Suomenlahdella samaan aikaan, mikä sitomiskyvystään. Myös lahtialueilla johtui veden epäorgaanisen typpi:fos- fosforipitoisuuksien lasku on johtanut fori-suhteen pienenemisestä. Plankto- siihen, että typen sitomiseen kykene-

nin kokonaismäärässä (a-klorofylli) mättömät sinilevälajit ovat saavutta- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 117 neet valta-aseman kasviplanktonyhtei- Kasvillisuuden muutoksia sössä. Saaristomerellä kasviplanktonin Kuormituksen aiheuttaman ravinnepi- kokonaismäärän lisääntyminen fosfo- toisuuksien kasvusta hyötyvät erityi- ripitoisuuksien kasvu seurauksena se- sesti rihmamaiset levät. Nopeakasvui- littyy sisäisellä kuormituksella ja län- sina lajeina ne pystyvät hyödyntämään tisen Suomenlahden ravinnevirtauksil- tehokkaasti nopeat esim. kumpuami- la Saaristomerelle. Sisäisen kuormituksesta johtuvat ravinnepulssit ja lisää- sen osuutta puolittain suljettujen altai- vät siten määrällistä osuuttaan leväyh- den hapettomuuteen ei ole selvitetty. teisöissä. Tämä on johtanut leväyhtei- Viime vuosina typpi/fosfori -suhteen sön lajistollisiin muutoksiin; rihma- vähentyminen ja typpirajoitteisuuden maiset lajit lisääntyvät ja monivuotiset lisääntyminen ovat luultavasti myötä- puna- ja ruskolevät vähenevät ja koko- vaikuttaneet sinilevien valta-aseman naislajimäärä pienenee. Myös levien voimistumiseen. selkeä vyöhykkeisyys esimerkiksi Saa- Suomenlahdella ja Saaristomerel- ristomerellä on muuttunut yhteisöra- lä myöhäiskesän sinileväkukintojen kenteen muuttuessa. Sisä- ja välisaaris- voimakkuus ja laajuus ovat lisäänty- tosta ovat rakkoleväyhteisöt kadonneet neet. Sinileväkukintoja on satunnaises- laajoilta alueilta. Nykyään sen tilalla ti havaittu myöskin myöhäissyksyllä ja kasvavat rihmamaiset rusko- ja viher- varhaistalvella. Perämerellä sinilevä- levät. Lisääntynyt orgaaninen aines on kukinnot ovat harvinaisia. Yleisimmät enenevässä määrin sedimentoitunut kukintoja muodostavat sinilevälajit pohjalle ja muuttanut sen laatua, jol- ovat Aphanizomenon ja toisinaan myr- loin putkilokasvien määrä lisääntyy. kyllinen Nodularia spumigena, jotka Irtonaisina kasvavien rihmalevi- kumpikin kykenevät sitomaan ilmake- en massaesiintymisiä (makrolevälaut- hästä veteen liuennutta typpeä. toja) on havaittu Merenkurkusta Itäi- Sinileväkukintojen muodostumi- selle Suomenlahdelle saakka. Erityises- nen kiihtyy usein kumpuamisten yh- ti Ahvenanmerellä ja Saaristomerellä teydessä, koska pohjalta veden tuotta- on havaittu makrolevämattojen peittä- vaan pintakerrokseen kulkeutuu run- vän laajoja alueita sekä Uudenkaupun- saasti fosforia. Kesällä 1997 olosuhteet gin saariston ja Eurajoen merialueella voimakkaiden sinileväkukintojen muo- esiintyi paljon suolilevän muodosta- dostumiselle olivat otolliset, koska tyy- mia irtonaisia kasvustoja. Suomenlah- net ja lämpimät säät vallitsivat ja pin- den makrolevälautat eivät ole olleet nan fosforipitoisuudet olivat koholla. niin laaja-alaisia ja monilajisia kuin Vuonna 1998 sinilevien kukintoja ha- Saaristo- ja Ahvenanmeren levälautat. vaittiin poikkeuksellisesti Saaristome- Levien massakasvustojen vaikutukset ren sisäosista, mikä on todennäköises- ovat kielteisiä, sillä ne aiheuttavat vir- ti yhteydessä typpirajoitteisuuden li- kistys- ja taloudellista haittaa. Patja- sääntymiseen Saaristomeren alueella. maisiksi kasvustoiksi muodostuneet Typpirajoitteisuus selittää sen miksi rihmalevät vaikeuttavat pohjaeläinyhtei- sinileväkukinnot muodostuvat monas- söjä ja patjan alle muodostuvat hapet- ti ulappavesillä. Avomereltä levälaut- tomat olosuhteet lisäävät pohjasedi- toja voi ajautua myöskin rantaan. Ran- mentistä vapautuvan fosforin määrää. nikon ja itäisen Suomenlahden Micro- Veden samentumisen seuraukse- cystis- ja Planktothrix-kukinnat vaativat na levien kasvusyvyydet ovat pienen- fosforin lisäksi myös epäorgaanista tyneet. Nykyisin kasvillisuutta tava-

typpeä ja sopivia sääoloja. taan Suomenlahden avoimilla rannoil- ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

118 ○○○○○○○○○○○○○ The Finnish Environment 472 la 10 metrin syvyyteen. Rakkolevä on Pohjaeläimet monivuotinen, isokokoinen ruskolevä, jonka tarjoama elinympäristö on tärkeä Rannikkovesien pohjien tilassa on monien eliölajien säilymiselle ranta- 1980-luvun jälkeen tapahtunut huo- vyöhykkeessä. Rakkolevän Suomen mattavia muutoksia. Kuormitetuilla puoleinen levinneisyysalue on Meren- alueilla muutossuunnat ovat kuitenkin kurkusta aina Itäiselle Suomenlahdel- varsin vaihtelevia. Useilla voimakkaas- le, Virolahdelle saakka. 1970-luvun lo- ti kuormitetuilla alueilla sisimmän saa- pussa havaittiin rakkolevän kadon- riston likaantuneeksi luokiteltu alue on neen monilta saaristoalueilta, mutta nykyään kaventunut, kun orgaanisen 1980-luvulla rakkoleväkasvustot toi- aineen ja fosforin kuormitus on alen- puivat monilla alueilla Saaristomerel- tunut. Suomenlahden keskiosan ranni- lä ja Suomenlahdella. Tästä huolimat- koilla, näiden pohjien tila on heiken- ta rakkolevä ei enää kasva yhtä syväl- tynyt voimakkaasti, vaikka pistemäi- lä kuin aikaisemmin. Rakkolevä kasvoi nen kuormitus onkin vähentynyt. Sel- Tvärminnen ulkosaaristossa 1930- ja vät alueelliset erot sisäsaariston pohji- 1960-luvulla vielä noin 10 metrin sy- en tilan kehityssuunnissa johtuvat jä- vyydessä, mutta 1990 luvulla rakkole- tevesikuormituksen muutosten lisäk- vä kasvoi 5–6 metrissä optimisyvyyden si myös rannikkovesien morfologiasta, ollessa 2–3 metrissä. Saarisomerellä pohjasedimentin laadusta ja veden se- rakkolevä kasvaa noin 1–4 metrin sy- koittumisoloista sekä läheisen avome- vyydessä, vaikka muutamia yksittäisiä ren tilasta. yksilöitä on tavattu 7–8 metrin syvyy- Ulommassa saaristossa pohja- dessä. eläinyhteisöjen tila on Pohjanlahdella muuttunut varsin vähän, mutta heikentynyt Saaristomerellä ja erityisesti Vieraslajit Suomenlahdella 1990-luvulla. Selvim- Suurin osa lajeista on saapunut laivo- mät merkit tästä ovat puhtaita vesiä jen painovesilastin mukana tai run- indikoivan valkokatkan vähentyminen koon kiinnittyneinä. Suomen rannik- sekä harvasukasmatojen ja surviais- kovesialueelta havaitut uudet tulokas- sääsken toukkien määrän lisääntymi- lajit ovat vakiintuneet 1990-luvulla alu- nen. Syynä on mm. pohjan happiolo- eelle. Pohjois-Amerikkalaista alkupe- jen heikkeneminen orgaanisen ainek- rää on pohjille asettunut monisukama- sen tuotannon lisääntymisen seurauk- to Marenzelleria viridis, Mustanmeren- sena. Hapettomat, kuolleet pohjat ovat- Kaspianmeren alueelta ovat peräisin kin olleet yleisiä laajoilla Suomenlah- vaeltajasimpukka Dreissena polymorpha, den alueilla 1990-luvun loppupuolel- halkoisjalkainen Hemimysis anomala ja la, mikä johtuu huomattavan suuresta petovesikirppu Cercopagis pengoi. Näis- niin sisäisestä kuin ulkoisestakin ravin- tä etenkin viimeksi mainittu on muo- nekuormituksesta. dostanut massaesiintymiä ja aiheutta- Rannikkovesien puhtaammilta nut taloudellista vahinkoa limoittamal- alueilta pohjaeläimistön seurantatulok- la kalastajien pyydyksiä ja verkkoja. sia on käytettävissä ainoastaan Hanko- Itämeren herkkyys näille tulokaslajeil- niemen länsipuolelta. Huomattavin le johtuu siitä, että Itämeri on verrat- muutos on siellä se, että kahden valta- tain nuori, vähälajinen ekosysteemi. lajin, valkokatkan ja liejusimpukan mää- Tulokaslajit saattavat muuttaa ekosys- räsuhteet ovat pitkän seurantajakson ai- teemin ravintoketjuja ja aiheuttaa ta- kana muuttuneet, ja jopa kääntyneet loudellista vahinkoa kalastukselle tai 1990-luvulla päinvastaisiksi edelliseen

tukkia vedenottojärjestelmiä. vuosikymmeneen verrattuna. Tämä, ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 119 samoin kuin joidenkin muiden lajien Haitalliset aineet määrämuutokset sopivat yhteen ran- nikkovesillä jatkuvan yleisen rehevöi- Suuret määrät raskasmetalleja, or- tymiskehityksen kanssa, mutta on kui- gaanisia yhdisteitä ym. haitallisia ai- tenkin huomattava, että nykyisenkal- neita on joutunut piste- ja hajakuormi- tainen valtalajikoostumus vallitsi alu- tuksen seurauksena Suomen rannikko- eella jo 1920-luvulla, joten muutoksiin vesiin. Tämä ilmenee pohjasedimentin täytyy olla muitakin syitä kuin vain ja eliöstön kohonneina pitoisuuksina. veden rehevöityminen, kuten esimer- Eliöstöön kertyvät haitalliset aineet kiksi lajien välinen ja lajien sisäinen voivat rikastua ravintoverkossa tai ai- kilpailu. heuttaa muutoksia lisääntymisessä, kasvussa ja aineenvaihdunnassa. Raskasmetallien, erityisesti lyijyn, Kalat ja kalastus kadmiumin ja elohopean, pitoisuudet Rehevöityminen vaikuttaa yleensä ka- sedimentissä jakautuvat alueellisesti lakantoihin siten, että kalojen määrä siten, että ne laskevat Pohjanlahdella kasvaa lisääntyneiden ravintovarojen pohjoisesta etelään päin ja Suomenlah- seurauksena. Rehevöityminen muut- della idästä länteen päin. Sedimentin taa kalakantojen rakennetta särkivaltai- elohopeapitoisuudet olivat korkeita semmaksi, parantaa joidenkin lajien Pohjanlahdella kun taas kadmiumpi- kasvua ja lisää poikasten ja pienten toisuudet Suomenlahdella. Suomen kalojen tuotantoa. Muutamat kalalajit rannikkovesien alueella raskasmetalli- kärsivät rehevöitymisestä. Ruskole- en maksimipitoisuudet olivat selvästi väyhdyskuntien katoaminen sameu- alle Itämeren huippuarvojen. Korkeita den vuoksi laajoilta pohja-aloilta on pitoisuuksia eliöstöstä on mitattu teol- heikentänyt mm. ahvenen ja hauen lisuusalueiden lähivesillä. Kilkin me- elinolosuhteita. Monet kalalajit välttä- tallipitoisuudet eivät poikenneet taus- vät vähähappisia vesiä. Rehevöitymi- tatasosta. Liejusimpukan kupari-, kad- sen haitalliset vaikutukset kaupalliseen mium- ja elohopeapitoisuudet olivat las- ja virkistyskalastukseen ilmenee kalas- kussa. Kalojen elohopeapitoisuudet ovat tajien pyydysten ja verkkojen tuhriin- myöskin vähentyneet selvästi teollisuu- tumisina ja limoittumisina sekä kalo- den kuormittamilla vesialueilla 1960- jen haju- ja makuhaittoina. ja 1970-lukujen aikana. Suolaisuus vaikuttaa myöskin Haitallisten orgaanisten yhdistei- kalakantojen rakenteeseen sekä kalojen den pitoisuudet sedimentissä olivat määrään ja esiintymiseen rannikolla. korkeita mm. sellu- ja petrokemian Itämeren suolaisuus on alentunut, kos- teollisuuden läheisyydessä. Vesiensuo- ka Itämereen ei ole Tanskan salmien jelutoimenpiteiden ansiosta näiden kautta tullut voimakkaita suolapulsse- yhdisteiden pitoisuudet sedimentissä ja 1980- ja 1990-lukujen aikana, lukuun ovat vähentyneet. Korkeita orgaanisten ottamatta vuoden 1993 kohtalaisen voi- yhdisteiden pitoisuuksia on mitattu makasta suolapulssia. Vähäinen suola- myös eliöstöstä. PCB:n ja DDT:n pitoi- pitoisuuden lasku Suomenlahdella ja suudet ovat yleisesti laskeneet Itäme- Saaristomerellä on epäsuorasti heijas- ren eliöstössä 1970-luvulta lähtien. Si- tunut silakan kasvun pienentymisenä, lakassa pitoisuuksien pieneneminen mikä johtuu silakan ravintokohteiden on hidastunut 1990-luvulla. määrän vähentymisenä. Tällä on talou- Petrokemian teollisuus on merkit- dellista merkitystä, sillä silakka on tär- tävä öljyperäisten yhdisteiden lähde.

kein kauppakala Suomessa. Pitoisuudet vedessä ovat yleensä olleet ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

120 ○○○○○○○○○○○○○ The Finnish Environment 472 määritysrajojen alapuolella 1980- ja lähes luonnontilaisia. Hyvään ja erin- 1990-lukujen aikana. Suurimmat öljy- omaiseen luokkaan kuuluvat alueet kat- pitoisuudet sedimentissä mitattiin teol- toivat avomeren ja suuren osan Pohjan- lisuuden lauhdevesiputkien ulkopuo- lahden rannikkoa. Noin 10 % merialu- lella. Petrokemian teollisuuden lähei- eesta kuului tyydyttävään luokkaan. syydessä kaloissa ei ole todettu nor- Alue sijaitsee Suomenlahden ja Saaris- maalia korkeampia pitoisuuksia. Öljy- tomeren rannikolla sekä Pohjanlahden peräisten yhdisteiden haitallisuus pe- kuormitetuilla alueilla. Ainoastaan rustuu siihen, että suurina pitoisuuk- yksi prosentti merialueesta kuului tyy- sina ne voivat aiheuttaa fysiologisia dyttävään luokkaan. Rehevöityminen oli muutoksia eliöstössä. tärkein syy veden laadun heikkenemi- seen, mikä ilmeni mm. korkeina a-klorofyllin pitoisuuksina, toistuvina levä- Rannikkovesien kukintoina tai pohjan happikatoina. käyttökelpoisuusluokitus Hygieniset indikaattoribakteerit heiken- Yleisen käyttökelpoisuusluokituksen sivät veden laatua muutamissa sisälah- mukaan lähes 90 % Suomen rannikko- dissa ja haitallisten aineiden kuten elo- vesistä kuului hyvään tai erinomaiseen hopean ja orgaanisten klooriyhdistei- laatuluokkaan, mikä on osoitus siitä den korkeat pitoisuudet joidenkin te-

että vesialueet ovat luonnontilaisia tai ollisuusalueiden edustoilla. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 121 References

Aaltonen, E.K. & Kalliolinna, M. 1990. Kokkolan edustan merialueen tila 1986-1989. Vaasan läänin vesiensuojeluyhdistys. 71 p. + app. Aarnio, K. & Bonsdorff, E. 1997. Passing the gut of juvenile flounder, Patichtys flesus: differential survival of zoobenthic prey species. Marine Biology 129: 11-14. Alasaarela, E. 1980. Phytoplankton and environmental conditions in the northern part of the Bothnian Bay. Acta Universitatis Ouluensis. Series A, no. 90, 23 p. AMAP, 1998. Arctic Monitoring and Assessment Programme, Oslo, 1998. Andersson, L. & Lepistö, L. 1998. Links between runoff generation, climate and nitrate-N leaching from forested catchments. Water, Air and Soil pollution 105: 227-237. Antikainen, S., Joukola, M. & Vuoristo, H. 2000. Water quality in Finland in the mid 1990s. Vesitalous Vol. 41, No. 2/ 2000. Helsinki. Antsulevich, A., Maximovich, N. & Vuorinen, I. 1999. Population structure, growth and reproduction of the common mussel (Mytilus edulis L.) off the Island of Seili (SW Fnland). Bor. Envir. Res. 4: 367-375. Anttila, R.1973. Effect of sewage on the fish fauna in the Helsinki area. Oikos 15: 226-229. Aro, E. 1998. Turska (Cod). Official Statistics of Finland, SVT Environment 1998:13: 10-13 (in Finnish). Barret, K. & Berge, E. (eds) 1996. Transboundary air pollution in Europe. EMEP, MSC-W Report 1/96, Part 2. Norwegian Meteorological Institute Research Report 32, Oslo. Bartnicki, J., Barrett, K., Tsyro, S., Erdman, L., Gusev, A., Dutchak, S., Pekar, M., Lükewille, A. & Krognes, T. 1998. Atmospheric supply of nitrogen, lead, cadmium, mercury and lindane to the Baltic Sea. EMEP/MSC-W Note 3/98. Bergström, U. & Björkqvist, L. 1997. Fucus vesiculosus communities in the northern Quark, northern Baltic Sea. - Abstracts of the BMB 15 and ECSA 27 Symposium, Mariehamn, Finland, 9-13 June 1997. p.34. Bonsdorff, E. 1992. Drifting algae and zoobenthos-effect on settling and community structure. Netherlands J. Sea Res. 30:57-62. Bonsdorff, E., Blomqvist, E.M., Mattila, J. & Norkko, A. 1997a. Long-term changes and coastal eutrophication. Examples from the Åland Islands and the Archipelago Sea, Northern Baltic Sea. Oceanologica Acta 20: 319-329. Bonsdorff, E., Blomqvist, E.M., Mattila, J. & Norkko, A. 1997b. Coastal Eutro-phication: Causes, consequences and perspectives in the Archipelago Areas of the Northern Baltic Sea. Estuarine, Coastal and Shelf Science 44: 63-72. Borg, H. & Jonsson, P. 1996. Large-scale metal distribution in Baltic Sea sediments. Mar. Poll. Bull. 32: 8-21. Boström, C. 1995. Flowering and fruit-bearing Zostera marina in Åland, Northern Baltic Sea. Mem. Soc. Fauna Flora Fenn. 71: 7-9. Boström, C. 1996. Evertebratfaunans samhällsstruktur i Zostera marina (L.) ängar - en analys i tid och rum. Pro gradu-avhandling, Inst för biol. Åbo Akademi. 87 p. Boström, C. & Bonsdorff, E. 1997. Community structure and spatial variation of benthic invertebrates associated with Zostera marina (L.) beds in SW Finland. J. Sea Res. 37: 153-166. Boström, C. & Mattila, M. 1999. The relative importance of food and shelterfor seagrass associated invertebrates - a latitudinal com-parison of habitat choice by isopod grazers. Oecologia 120: 162-170. Boström, C., Bonsdorff, E., Kangas, P. & Norkko, A. 1997. Long-term changes in an eelgrass (Zostera marina L.) community in the northern Baltic Sea. - Abstracts of the BMB 15 and ECSA 27 Symposium, Mariehamn, Finland, 9-13 June 1997. p.35. Bäck, S., Collins, J.C.C. & Russell, G. 1991. Aspects of the reproductive biology of Fucus

vesiculosus from the coast of SW Finland. Ophelia 34: 129-141. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

122 ○○○○○○○○○○○○○ The Finnish Environment 472 Bäck, S., Lehvo, A. & Kiirikki, M. 1993a. The occurrence of macroalgal mass blooms on the Finnish Baltic coast. -In: Rijsteinbil, J.W. & Haritonidis, S. (eds). Macroalgae, eutrophication and trace metals cycling in estuaries and lagoons. Proc. of the COST- 48 Symposium of Sub Group III. 24-26 September 1993. Bridge. Commision of the European Communities. Bäck, S., Mäkinen, A., Rissanen, J. & Rönnberg, O. 1993b. Phytobenthos monitoring. Two case studies from the Finnish Baltic coast in summer 1993. Ministry of the Environment. Finland. Memorandum 1993: 1-24. Bäck, S. & Ruuskanen, A. 2000. Distribution and maximum growth depth of Fucus vesiculosus along the Gulf of Finland. Mar. Biol. 136: 303-307. Bäck, S., Lehvo, A. & Blomster, J. 2000. Mass occurrence of unattached Enteromorpha intestinalis on the Finnish Baltic coast. Annales Bot. Fennici 37: 155-161. Böhling, P. & Ådjers, K. 1998. Merialueen ahven (Perch in coastal waters). Official Statistics of Finland, SVT Environment 1998:13: 46-49 (in Finnish). Enckell-Sarkola, E., Pitkänen, H. & Wrådhe, H. 1989. The metal load on the Gulf of Bothnia. Vesi- ja Ympäristöhallituksen monistesarja 291. 44 p. Erkkilä, H. & Vaajakorpi, H. 1993. Porvoon edustan merialueen tarkkailu vuonna 1992. Vesihydro Oy. 53 p. + app. Erkkilä, H. & Vaajakorpi, H. 1999. Porvoon edustan merialueen tarkkailu vuonna 1998. Laaja vuosiyhteenveto 31.5.1999. Vesihydro Oy. 40 p. + app. Ferin-Westerholm, P. (ed.) 1994. Ympäristön tila Pohjois-Pohjanmaalla ja Kainuussa.. Vesi- ja ympäristöhallitus, Ympäristötietokeskus, alueelliset tilaraportit 2, Helsinki. Finnish statistical yearbook of forestry. (in Finnish): Metsätilastollinen vuosikirja 1997. Suomen virallinen tilasto. Maa- ja metsätalous 1997:4. Helsinki 1997. Flinkman, J., Aro, E., Vuorinen, I. & Viitasalo, M. 1998. Changes in northern Baltic zooplankton and herring nutrition from 1980s to 1990s: top-down and bottom-up processes at work. Mar. Ecol. Prog. Ser. 165: 127-136. Forsberg, C., Ryding, S.-O., Claesson, A. & Forsberg, Å. 1978. Water chemical analyses and/or algal assay? Sewage effluent and polluted lake water studies. Mitt. int. Verein. Limnol. 21: 352-363. Grönlund, L. & Leppänen, J.-M. 1990. Long-term changes in the nutrient reserves and pelagic production in the western Gulf of Finland. Finnish Mar. Res. 257: 15-27. Haahtela, I. 1984. A hypothesis of the decline of the bladderwrack (Fucus vesiculosus L.) in SW Finland in 1975-1981. Limnologica 15: 345-350. Haahtela, I. & Lehto, J. 1982. The occurrence of bladder wrack (Fucus vesiculosus) in 1975- 1980 in the Seili area, Archipelago Sea. Mem. Soc. Fauna Flora Fennica 58:1-5. Haasala, K. & Kauppinen, V. 1995. Kemin edustan merialueen biologinen seuranta v. 1994. Pohjois-Suomen vesitutkimustoimisto. 25 p. + app. Hario, M., Hollmen, T., Kilpi, M., Lehtonen, J.T., Mustonen, O., Westerbom, M. & Öst, M. 1999: Riittääkö haahkalle ravintoa Suomenlahdella? Suomen Riista 45:34-45. Heinonen P. & Herve S. 1987. Water quality classification of inland waters in Finland. Aqua Fennica 17,2:147-156. Heitto, L. & Anttila-Huhtinen, M. 1995. Haitalliset aineet Kymijoella ja sen edustan merialueella. Raportti vuoden 1994 velvoitetarkkailutuloksista. Kymijoen Vesiensuojeluyhdistys. Käsikirjoitus. HELCOM 1993. First assessment of the state of the coastal waters of the Baltic Sea. Baltic Sea Env. Proc. 54: 1-155. HELCOM 1996. Third periodic assessment of the state of the marine environment of the Baltic Sea, 1989- 93; Background document. Baltic Sea Env. Proc. 64 B: 1-252. HELCOM 1998. The third Baltic Sea pollution load compilation (PLC-3). Baltic Sea Env. Proc. 70: 1-133. Helminen, H., Juntura, E., Koponen, J., Laihonen, P. & Ylinen, H. 1998. Itämereltä saaristomereen tulevan fosfori- ja typpikuormituksen arviointi kolmiulotteisen virtausmallin avulla. Vesitalous 2: 27-30. Heiskanen 1998. Factors governing sedimentation and pelagic nutrient cycles in the

northern Baltic Sea. Doc. thesis. Helsinki 1998, 80 p. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 123 Henriksson S.-H. 1991. Effects of fish farming on natural Baltic fish communities. In: Mäkinen, T. (ed.). Marine aquaculture and environment. Nordic Council of Ministers. Nord 22: 85-104. Holm, N.G. 1988. Arsenic regeneration from estuarine sediments of the Bothnian Bay, Sweden. Chem. Geol. 68: 89-98. Holmström, A., Norkko, A. & Bonsdorff, E. 1997. Drift algal mats - field and laboratory studies of occurrence, biomass, species composition and decomposition. - Abstracts of the BMB 15 and ECSA 27 Symposium, Mariehamn, Finland, 9-13 June 1997. p. 43. Hudd, R., Kjellman, J. & Urho, L. 1996. The increase of coincidence in relative year-class strengths of coastal perch (Perca fluviatilis L.) stocks in the Baltic Sea. Ann. Zool. Fennici 33: 383-387. Häkkilä, K. 1984. Pohjasedimentin ja simpukoiden raskasmetallipitoisuuksia Selkämeren eteläosan rannikolla. Vesihallituksen monistesarja 303: 1-33. Häkkilä, K. 1985. Pohjasedimentin ja simpukoiden raskasmetallipitoisuuksista Selkämeren eteläosan rannikolla. Vesihallituksen monistesarja 380: 38 p. Häkkilä, K. 1998. Leväkukinnat Lounais-Suomen ympäristökeskuksen alueella. In: Rantajärvi, E. (ed.) Leväkukintatilanne Suomen merialueilla ja varsinaisella Itämerellä vuonna 1997. Meri 36: 1- 32. Hällfors, G., Niemi, Å., Ackefors, H., Lassig, J. & Leppäkoski, E. 1981. Chapter 5, Biological Oceanography. In: Voipio, A. (ed.). The Baltic Sea. Elsevier Oceanography Series, 30. 418 pp. Hällfors, G., Kangas, P. & Niemi, Å. 1984. Recent changes in the phytal at the southern coast of Finland. Ophelia 3:51-59. Hänninen, J., Kirkkala, T. & Lehtilä, K. 1997. Fosfori- ja typpipitoisuuksien pitkäaikais- muutoksista Saaristomerellä. Vesitalous 5: 17-22. Hökkä, M. & Rantala, L. 1992. Oulun edusta. Velvoitetarkkailun yhteenveto v. 1988-1991. Pohjois-Suomen vesitutkimustoimisto. 55 p. + app. Ilus, E. 1997. Loviisan ydinvoimalaitosta ympäröivän merialueen biologinen tarkkailu vuonna 1996. Säteilyturvakeskus. 31 p. + app. Isosaari, P., Kiviranta, H., Kohonen, T., Salonen, V.-P., Tuomisto, J. & Vartiainen, T. 1999. Environmental distribution of PCDD/Fs from vinylchloride monomer production: a case study. Organohalogen Compounds 41: 417-420. Jankovski, H., Simm, M. & Roots, O. 1996. Harmful substances in the ecosystem of the Gulf of Finland. Estonian Marine Institute. EMI reports series, No 4. Tallinn. 1996. Jumppanen, K. 1993. Uudenkaupungin merialueen kuormitus ja tila vuonna 1992. Lounais-Suomen vesiensuojeluyhdistys 82: 38 p. Jumppanen, K. 1997a. Uudenkaupungin merialueen kuormitus ja tila vuonna 1996. Lounais-Suomen vesiensuojeluyhdistys. 48 p. + app. Jumppanen, K. 1997b. Uudenkaupungin merialueen pohjaeläintutkimus vuonna 1996. Lounais-Suomen vesiensuojeluyhdistys. Tutkimusselosteita 128. 30 p. + app. Järvinen, O. & Vänni, T. 1997. Sadeveden pitoisuus- ja laskeuma-arvot Suomessa vuonna 1995. Suomen ympäristökeskuksen moniste 78. Helsinki, 68 pp. Kahru, M., Horstmann, U. & Rud, O. 1994. Satellite detection of increased cyanobacteria blooms in the Baltic Sea: Natural fluctuations or ecosystem change? Ambio 23: 469- 472. Kalliolinna, M. 1998. Kokkolan edustan yhteistarkkailun tulokset 1997. Pohjanmaan vesiensuojeluyhdisty ry. Pietarsaari 1998, 27 p. + 8 app. Kalliolinna, M. & Aaltonen, E.-K. 1991. Pietarsaaren edustan velvoitetarkkailun yhteenveto 1990. Vaasan läänin vesiensuojeluyhdistys ry Kalliolinna, M. & Aaltonen, E.-K. 1995. Kokkolan edustan merialueen tila 1990-1994. Vaasan läänin vesiensuojeluyhdistys. 85 p. + app. Kangas, P. & Niemi, Å. 1985. Observations of recolonization by the bladderwrack, Fucus vesiculosus, on the southern coast of Finland. Aqua Fennica 15:133-141. Kangas, P., Autio, H., Hällfors, G., Luther, H., Niemi, Å. & Salemaa, H. 1982. A general model of the decline of Fucus vesiculosus at Tvärminne, south coast of Finland in 1977-81. Acta Bot. Fenn. 118: 1-27. Kankaanpää, H. 1997. Sedimentation, distribution, sources and properties of organic

halogen material in the Gulf of Finland. Bor. Ecol. Res. Monographs, no 6. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

124 ○○○○○○○○○○○○○ The Finnish Environment 472 Kauppi, L. 1979. Phosphorus and nitrogen input from rural population, agriculture and forest fertilization to watercourses. Publication of the Water Research Institute, National Board of Waters, Finland 34: 35-46. Kauppi, L. (toim.) 1993. Itäisen Suomenlahden lintukuolemat keväällä 1992. Vesi- ja Ympäristöhallitus, Helsinki. Vesi- ja ympäristöhallinnon julkaisuja - sarja A, no 142, 46 p. Kauppila, P., Hällfors, G, Kangas, P., Kokkonen, P. & Basova, S. 1995. Late summer phytoplankton species composition and biomasses in the eastern Gulf of Finland. Ophelia 42: 179-191. Kauppila, P. & Lepistö, L. 1997. Levätilanne Suomen rannikkovesissä. In: Rantajärvi, E. (ed.). Leväkukintatilanne Suomen merialueilla ja varsinaisella Itämerellä vuonna 1996. Meri 29: 11-12. Kauppila, P. & Lepistö, L. 1998. Levätilanne Suomen rannikkovesissä. In: Rantajärvi, E. (ed.). Leväkukintatilanne Suomen merialueilla ja varsinaisella Itämerellä vuonna 1997. Meri 36: 13-14. Kauppinen, V. 1987. Tornion edustan kalataloustutkimukset v. 1986. II Kalataloustarkkailu. Pohjois-Suomen vesitutkimustoimisto. 17 p. + app. Kauppinen, V. 1991a. Oulun edustan merialueen pohjaeläinselvitys v. 1991. Pohjois- Suomen vesitutkimustoimisto. 21 p. + app. Kauppinen, V. 1991b. Raahen edustan merialueen kalataloudellinen velvoitetarkkailu v. 1990. Pohjois-Suomen vesitutkimustoimisto. 25 p. + app. Kauppinen, V. 1994. Raahen edustan merialueen kalataloudellinen velvoitetarkkailu v. 1993. Pohjois-Suomen vesitutkimustoimisto. 27 p. + app. Kauppinen, V. 1995. Tornion edustan merialue. II Kalataloustarkkailu v. 1992-1994. Pohjois-Suomen vesitutkimustoimisto. 29 p. + app. Kauppinen, V. 1997. Tornion edustan merialue. III Kalat ja kalastus v. 1996. PSV-Maa ja Vesi. 26 p. + app. Kautsky, H. 1995. Vegetationsklädda bottnar. - Östersjö ’94. Årsrapport från den marina miljöövervakning-en juli 1995. Stockholms Marina Forskningscentrum. pp. 23-25. Kautsky, L.1982. Primary production and uptake kinetics of ammonium and phosphate by Enteromorpha compressa in an ammonium sulphate industry outlet area. Aquatic Botany 12: 23-40. Kautsky, N., Kautsky,H., Kautsky, U. & Waern, M. 1986. Decreased depth penetration of Fucus vesiculosus (L.) since 1940s indicates eutrophication of the Baltic Sea. Mar. Ecol. Prog. Ser. 28: 1-8. Keinänen, M., Tolonen, T., Ikonen, E., Parmanne, R., Tigerstedt, C., Ryti-lahti, J., Soivio, A. & Vuorinen, P.J. 2000. Itämeren lohen lisääntymishäiriö -M74. Kalatutkimuksia, Fiskundersökningar 165. Riista- ja kalatalouden tutkimuslaitos. Kenttämies, K. & Vilhunen, O. 1999. Metsätalouden fosfori- ja typpikuormitus vuosina 1977-1996 ja arvio kuormituksen kehittymisestä vuoteen 2005 erityisesti Oulujärven vesistöalueella. In: Metsätalouden ympäristökuormitus. Seminaari Nurmeksessa 23. - 24.9.1998. Tutkimusohjelman väliraportti. Metsäntutkimuslaitoksen tiedonantoja 745: 115-126. Kiirikki, M. & Blomster, J. 1996. Wind induced upwelling as a possible explanation for mass occurrences of epiphytic Ectocarpus siliculosus (Phaeophyta) in the northern Baltic Proper. Mar. Biol. 127: 353-358. Kiirikki, M. & Lehvo, A. 1997. Life strategies of filamentous algae in the northern Baltic Proper. Sarsia 82:259-267. Kirkkala, T. 1998. Miten voit Saaristomeri? Ympäristön tila Lounais-Suomessa 1. Lounais- Suomen ympäristökeskus. 70 p. Kirkkala, T., Helminen, H. & Erkkilä, A. 1998. Variability of nutrient limitation in the Archipelago Sea, SW Finland. Hydrobiologia 363: 117-126. Kivi, K., Kaitala, S., Kuosa, H., Kuparinen, J., Leskinen, E., Lignell, R., Marcussen, B. & Tamminen, T. 1993. Nutrient limitation and grazing control of the Baltic plankton communcty during annual succession. Limnol. Oceanogr. 38: 893-905. Kjellman, J., Hudd, R., Leskelä, A., Salmi, J. & Lehtonen, H. 1994. Estimation and prognosis of recruitment failures due to episodic acidification on burbot (Lota lota

L.) of the River Kyröjoki. Aqua Fennica 24: 51-57. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 125 Koistinen, M. 1989. Vesikasvillisuus Hankoniemen pohjoispuolen merialueella, teollisuuden ammoniumpäästöjen vaikutuspiirissä v. 1988. Vesi- ja ympäristöhallituksen monistesarja 186: 1-149. Koivisto, V. M. & Blomqvist, E. M. 1988. Does fish farming affect natural Baltic fish communities? Kieler Meeresforsch., Sonderh. 6: 301-311. Kokemäenjoen vesistön vesiensuojeluyhdistys ry. 1995. Kokemäenjoen ja Porin edustan merialueen yhteistarkkailu: sedimentin metallipitoisuudet kokemäenjoessa, Pihlavanlahdella ja Ahlaisten saaristossa vuonna 1995. Koli, L., Rask, M., Viljanen, M. & Aro, E. 1988: The diet of perch, Perca fluviatilis L., at Tvärminne, northern Baltic Sea, and a comparison with two lakes. - Aqua Fennica 18: 185-191. Kononen, K. 1992. Dynamics of the toxic cyanobacterial blooms in the Baltic Sea. Finnish Marine Research 261: 1-36. Korhonen, M., Verta, M., Lehtoranta, J., Kiviranta, H. & Vartiainen, T. 1999. The levels of PCDD/Fs in fish in river Kymijoki polluted by Ky-5 manufacturing. Organohalogen Compounds 41: 431-433. Kukk, H. & Viitasalo, I. 1997. The convalescence of Seurasaari Bay: recovery of macrophyte vegetation took fifteen years after closing the wastewater sewers. Abstracts of the BMB 15 and ECSA 27 Symposium, Mariehamn, Finland, 9-13 June 1997. p.13. Kyröläinen, H. 1995. Vaasan edustan merialueen yhteistarkkailu. Vuosiyhteenveto 1994. Vaasan kaupunki ympäristölaboratorio. Kyröläinen, H. 1996.Vaasan edustan merialueen yhteistarkkailu. Vuosiyhteenveto 1995. Vaasan kaupunki ympäristölaboratorio. Kähäri, J., Mäntylahti, V. & Rannikko, M. 1987. Soil fertility of Finnish cultivated soils. Viljavuuspalvelu Oy. Helsinki 1987. 105 p. Kärkkäinen, A. 1995. Kemira Pigments Oy. Po rin edustan merialueen pohjaeläimistö 1994. Kokemäenjoen vesistön vesiensuojeluyhdistys. 37 p. + app. Kääriä, J., Eklund, J., Hallikainen, S., Kääriä, R., Rajasilta, M., Ranta-aho, K. & Soikkeli, M. 1988. Effects of coastal eutrophication on the spawning grounds of the Baltic herring in the SW archipelago of Finland. Kieler Meeresforsch. 6: 348-356. Lampolahti, J. 1997. Uudenkaupungin merialueen kasvillisuuden kehitys 1990-1996. Tutkimusraportti Kemira Agro Oy:n Uudenkaupungin tehtaille. 30 p. + 36 figs.. Langi, A. & Paavilainen, K. 1996. Kaskisten merialueen velvoitetarkkailu vuonna 1995. KCL Ekolab. 18 p. + app. Lapp, B. & Baltzer, W. 1993. Early diagenesis of trace metals used as an indicator of past productivity changes in coastal sediments. Geochim. Cosmochim. Acta 57: 4639- 4652. Lappalainen, A., Rask, M., Koponen, H. & Vesala, S. 2000a. Relative abundance, diet and growth of perch (Perca fluviatilis) and roach (Rutilus rutilus) at Tvärminne, northern Baltic Sea – comparison between years 1975 and 1997. (submitted manuscript). Lappalainen, A., Shurukhin, A., Alekseev, G. & Rinne, J. 2000 b. Coastal fish communities along the northern coast of the Gulf of Finland, Baltic Sea: responses to salinity and eutrophication (submitted in Int. Rev. Hydrobiol.). Lappalainen, A. & Pesonen, L. 1998. Veden laadun paranemisesta huolimatta Helsingin ja Espoon lahtialueiden kalasto muuttuu hitaasti. Vesitalous 5/1998, p. 32-35. Lappalainen, A. & Pönni, J. 1996. Suomenlahti kalastajien silmin - vesien likaantumien ja kalastus Suomenlahdella. Kalatutkimuksia 107, 44 pp. Lappalainen, A. & Pönni, J. 2000. Eutrophication and recreational fishing on the Finnish coast of the Gulf of Finland: mail survey. Fishes, Man and Ecol. 7: 323-335. Lappalainen, A., Hällfors, G. & Kangas, P. 1977. Littoral benthos of the Northern Baltic Sea. IV Pattern and dynamics of macrobenthos in a sandy-bottom Zostera marina community in Tvärminne. Int. Rev. Ges. Hydrobiol. 62: 465-503 Lehtonen, H. 1985. Changes in commercially important freah water fish stocks in the Gulf of Finland during recent decades. Finnish Fish. Res. 6: 61-70. Lehvo, A. & Bäck, S. 2001: Survey of macroalgal mats on southeastern Baltic coast of Finland. Aquatic Conservation 11:11-18 Lehvo, A. & Bäck, S. 2000: Notes on sublittoral vegetation in the vicinity of the Vyborg Bay,

Russia. Mem. Soc. Fauna Flora Fennici 76: 7-13. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

126 ○○○○○○○○○○○○○ The Finnish Environment 472 Leivuori, M. & Niemistö, L. 1995. Sedimentation of trace metals in the Gulf of Bothnia. Chemosphere 31: 3839-3856. Leivuori, Mirja; Puhakainen, Tanja; Riikonen, Jere 1997: Heavy metals in Baltic herring. Kemia 97. Kemian Päivät, Helsinki. Abstraktit:39 Leppäkoski, E. 1975. Assessment of degree of pollution on the basis of macrozoobenthos in marine and brackish water environments. Acta Acad. Aboensis B 35. Lindholm, T. 1992. Ecological role of depth maxima of phytoplankton. Arch. Hydrobiol. Beih. Ergebn. Limnol. 35: 33-45. Lindholm, T. & Virtanen, T. 1992. A bloom of Prymnesium parvum Carter in a small coastal inlet in Dragsfjärd, southwestern Finland. Environmental Toxicology and Water Quality. 7 (2): 165-170. Littorin, B. & Gilek, M. 1997. A photographic documentation of the recolonisation of cleared patches in a dense population of Mytilus edulis in the northern Baltic proper. Abstracts of the BMB 15 and ECSA 27 Symposium, Mariehamn, Finland, 9-13 June 1997. p.15. Lounais Suomen Vesiensuojeluyhdistys ry. 1995. Rauman edustan sedimentti- ja pohjaeläintutkimukset.1994 Miettinen, P., Holmberg, R., Jokinen, O., Ranta, E. & Kuosa, H. 1994. Mustionjoen, Fiskarsinjoen, Pohjanpitäjänlahden ja Tammisaaren merialueen yhteistarkkailun yhteenveto vuodelta 1993. Länsi-Uudenmaan vesi- ja ympäristö, julk no 38a. Munsterhjelm, R. 1997. The aquatic macrophyte vegetation of flads and gloes, S coast of Finland. Acta Bot. Fennica 157:1-68. Mäkinen, A., Haahtela, I., Ilvessalo, H., Lehto, J. & Rönnberg, O. 1984. Changes in the littoral rocky shore vegetation in the Seili area, SW Archipelago of Finland. Ophelia Supplement 3:157-166. Mäkinen, A., Hänninen, J. & Vahteri, P. 1994. Saaristomeren kansallispuiston vedenalaisen luonnon kartoitus ja litoraalin kasvillisuuden seuranta. Saaristomeren tutkimuslaitos, Turun yliopisto. Väliraportti 1994. Mäkinen, T. (toim.) 1998. Kalankasvatuksen ympäristökuormitustavoitteet ja oikeudel- linen ohjaus Saaristomerellä ja Ahvenanmerellä. Suomen ympäristökeskuksen moniste, no 133, 44 s. Nakari, T. 1992. Porvoon edustan merialueen meriveden vaikutuksista sumputettujen ja luonnonkalojen elintoimintoihin. Vesi- ja Ympäristöhallinnon julkaisuja -sarja A, no 94, 175 s. National Board of Waters 1983. Vesistöjen tila 1980-luvun alussa. Vesiensuojelun tavoiteohjelman osaprojekti n:o 7. National Board of Waters Report No. 194, Helsinki. National Board of Waters and the Environment 1988. Vesistöjen laadullisen käyttökelpoi- suuden luokittaminen. Publications of Water and Environment Administration No. 20, Helsinki. Nehring, D. & Matthaus, W. 1991. Current trends in hydrographic and chemical parameters and eutrophication in the Baltic Sea. Int. Revue ges. Hydrobiol. 76: 297- 316. Niemi, Å. 1973. Ecology of phytoplankton in the Tvärminne area, SW coast of Finland. I. Dynamics of hydrography, nutrients, chlorophyll a and phytoplankton. Acta Bot. Fennica 100: 1-68. Niemi, Å. 1988. Exceptional mass occurrence of Microcystis aeruginosa (Kützing) Kützing (Chroococcales, Cyanophyceae) in the Gulf of Finland in autumn 1987. Mem. Soc. Fauna Flora Fennica 64: 165-167. Niemi J.S., Niemi R.M., Malin V. & Poikolainen M.-L. 1997. Bacteriological quality of Finnish rivers and lakes. Environ. Toxicol Water Qual. 12:15-21. Niemi, J., Heinonen, P., Mitikka, S. Vuoristo, H., Pietiläinen, O-P., Puupponen, M. & Rönkä, E. 2000. The Finnish EUROWATERNET: The European agencys monitoring network for Finnish inland waters. The Finnish Environment 445, 62 p. Norha, T. 1998. Helsingin ja Espoon merialueen pohjaeläimistö vuonna 1997. In: Pesonen, L. (ed.). Helsingin ja Espoon merialueiden velvoitetarkkailu vuonna 1997.

Helsingin kaupungin ympäristökeskuksen julkaisuja 4/98. p 71-86. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 127 Norkko, A. & Bonsdorff, E. 1996a. Rapid zoobenthic community responses to accumulations of drifting algae. Mar. Ecol. Prog. Ser. 131:143-157. Norkko, A. & Bonsdorff, E. 1996b. Rapid zoobenthic community responses to accumulations of drifting algae. Mar. Ecol. Prog. Ser. 131:143-157. Oravainen, 1996. Vuosiyhteenveto Kokemäenjoen ja Porin edustan merialueen yhteistarkkailusta vuodelta 1995. Kokemäenjoen vesistön vesiensuojeluyhdistys. 36 p. + app. Orlova, M.I., Anokhina, L.E., Panov, V.E., Nekrasov, A.Y. & Klimentenok, S.N. 1999. Preliminary environmental state assessment for littoral zone in resort district of St. Petersburg (Eastern Gulf of Finland). BFU (Baltic Floating University) Research Bulletin. 3: 37-42. Owens, J.W. & Lehtinen, K-J. 1995. Assessing the potential impacts of pulping and bleaching operations on the aquatic environment-TAPPI book series. Paavilainen, K., Tana, J., Kovanen, V. & Pogreboff, S. 1985. OY Metsä-Botnia AB, Kaskinen 1985. Tutkimus jätevesien vaikutuksista merialueen veden laatuun ja kalatalouteen Oy Keskuslaboratorio - Centrallaboratorium Ab. Paavilainen, K., Langi, A. & Tana, J. 1985. Effect of pulp and paper mill effluents on a fishery in the Gulf of Finland. Finnish Fish. Res. 6: 81-91. Palm, H. & Lammi, R. 1995. Fate of pulp mill organochlorines in the Gulf of Bothnia sediments. Environment Science and Technology. 29: 1722-1727. Parmanne, R. 1999. The spawning time and composition of spawning shoals according to trapnet fishing of Baltic herring. Kalatutkimuksia 159, 41 pp. (in Finnish with English summary). Partanen, P. 1993. Pohjaeläintutkimukset Konnivedellä, Kymijoella sekä Pyhtään, Kotkan ja Haminan merialueilla v. 1992. Kymijoen vesiensuojeluyhdistys. 39 p. + app. Patrikainen, M. 1991. Sedimentin ja pohjaeläimien titaani- ja vanadiinipitoisuudet Porin edustan merialueella 1989-90. - Kokemäenjoen vesistön vesiensuojeluyhdistys ry. Perttilä, M., Savchuck, O. & Sphaer, I. 1996. Gulf of Finland, Hydrochemistry. HELCOM, 1996. Third periodic assessment of the state of the marine environment of the Baltic Sea, 1989-1993; Background document. Baltic Sea Environ. Proc. 64B: 48-51. Perttilä, M. & Brygman, L. 1992. Review of contaminants on Baltic sediments. ICES Coop. Res. Rep. 180. Pesonen, L. 1999 (toim.). Helsingin ja Espoon merilaueiden velvoitetarkkailu vuonna 1998. Helsingin kaupungin ympäristökeskuksen monisteita 5/99. 81+ 4 app. Pesonen, L. 1998 (toim.). Helsingin ja Espoon merialueiden velvoitetarkkailu vuonna 1997. Helsingin kaupungin ympäristökeskuksen julkaisuja 4/98. 101+ 4 app. Pesonen, L., Norha, T., Rinne, I., Viitasalo, I. & Viljamaa, H. 1995. Helsingin ja Espoon merialueiden velvoitetarkkailu vuosina 1987-1994. Helsingin kaupungin ympäristökeskuksen monisteita 1. 143 p. + app. Piiroinen, O. 1987. Kokemäenjoen alajuoksun yhteistarkkailu. Haukien elohopeapitoisuudet ja sedimentin raskasmetallipitoisuudet Kokemäenjoessa ja Pihlavanlahdella. 1985. Kokemäenjoen vesistön Vesiensuojeluyhdistys r.y. Piiroinen, O. 1992a. Kokemäen alajuoksun yhteistarkkailu. Sedimentin metallipitoisuudet Kokemäenjoessa, Pihlavanlahdella ja Ahlaisten saaristossa 1991. Kokemäenjoen vesistön Vesiensuojeluyhdistys ry. Piiroinen, O. 1992b. Kokemäen ja sen edustan merialueen kalataloudellinen tarkkailu: Kirjanpitokalastus 1989-90 ja haukien elohopeapitoisuudet 1991. Kokemäenjoen vesistön Vesiensuojeluyhdistys ry julkaisu nro 255. Piiroinen, O. 1995. Kokemäenjoen ja sen edustan merialueen kalataloudellinen tarkkailu: kirjanpitokalastus 1993-1994 ja haukien elohopeapitoisuudet 1993-1994. Kokemäenjoen vesistön Vesiensuojeluyhdistys ry. Pitkänen, H. 1991. Nutrient dynamics and trophic conditions in the eastern Gulf of Finland: The regulatory role of the Neva estuary. Aqua Fennica 21: 105-115. Pitkänen, H. 1994. Eutrophication of the Finnish coastal waters: Origin, fate and effects of riverine nutrient fluxes. National Board of Waters and the Environment, Finland.

Publications of the Water and Environment Research Institute, no. 18:1-44. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

128 ○○○○○○○○○○○○○ The Finnish Environment 472 Pitkänen, H., Kangas, P., Miettinen, V. & Ekholm, P.1987. The state of the Finnish coastal waters in 1979-83. National Board of Waters and the Environment, Finland. Publications of the Water and Environment Administration, no. 8, 167 p. Pitkänen, H., Kangas, P., Sarkkula, J., Lepistö, L., Hällfors, G. & Kauppila, P. 1990. Veden laatu ja rehevyys itäisellä Suomenlahdella. Raportti vuosien 1987-88 tutkimuksista. Vesi- ja Ympäristöhallitus, Vesi- ja ympäristöhallinnon julkaisuja - sarja A, no 50, 137 s. (with an English summary) Pitkänen, H., Tamminen, T., Kangas, P., Huttula, T., Kivi, K., Kuosa, H., Sarkkula, J., Eloheimo, K., Kauppila, P. & Skakalsky, B. 1993. Late summer trophic conditions in the northeast Gulf of Finland and the River Neva Estuary, Baltic Sea. Estuarine, Coastal and Shelf Sci. 37: 453-474. Pitkänen, H. & Tamminen, T. 1995. Nitrogen and phosphorus as production limiting factors in the estuarine waters of the eastern Gulf of Finland. Mar. Ecol. Prog. Ser. 129: 283-294. Pitkänen, H., Kondratyev, S., Lääne, A., Gran, V., Kauppila, P., Loigu, E., Markovets, I., Pachel, K. & Rumyantsev, V. 1997. Pollution load on the Gulf of Finland from Estonia, Finland and Russia in 1985-1995. In: J. Sarkkula (ed.). Proceedings of the Final Seminar of the Gulf of Finland Year 1996, March 17-18, 1997 Helsinki. Suomen Ympäristökeskuksen moniste 105: 9-18. Pitkänen, H. & Välipakka, P. 1997. Extensive deep water oxygen deficit and bethic phosphorus release in the Eastern Gulf of Finland in late summer 1996. In: J. Sarkkula (ed.). Proceedings of the Final Seminar of the Gulf of Finland Year 1996, March 17-18, 1997 Helsinki. Suomen Ympäristökeskuksen moniste 105: 51-59. Pouchet, G. & de Guerne, J. 1885. Sur la faune pélagique de la mer Baltique et du Golfe de Finlande. Comptes rend. des séances de l’Académie des Sciences 100: 919-921. Pulliainen, E., Korhonen, K. & Huuskonen, M. 1999. Perämeren mateiden sukurauhasten kehityshäiriöt. Ongelman laajuus ja yhteydet muiden kalojen lisääntymishäiriöihin. Suomen ympäristö No. 322. Puomio, E.-R. & Braunschweiler, S. 1993. Uudenmaan ja Etelä-Hämeen vesistöjen tila 1990- luvun alussa. National Board of Waters and the Environment Report No. 501, Helsinki. Puomio E.-R., Soininen J. & Takalo S. 1999. Uudenmaan ja Itä-Uudenmaan vesistöjen tila 1990-luvun puolivälissä. Regional Environmental Publications 128. Uusimaa Regional Environment Centre, Helsinki. Purasjoki, K. 1935. Merilevien vertikaalisesta esiintymisestä Tvärminnessä. - Master thesis. Univ. of Helsinki. 118 pp. (In Finnish). Pönni, J. 1998a. Silakka (Baltic herring). Official Statistics of Finland, SVT Environment 1998:13: 2-6. Pönni, J. 1998b. Kilohaili (Sprat). Official Statistics of Finland, SVT Environment 1998:13: 7-9. Raita, A. & Silvonen, J. 1997. Loviisan voimalaitos. Jäähdytys- ja jätevesien tarkkailu- raportti 1996. Imatran voima Oy. 13 p. + app. Rajasilta, M., Eklund, J., Kääriä, J. & Ranta-Aho, K. 1989. The deposition and mortality of the eggs of the Baltic herring, Clupea harengus membras L., on different substrates in the south-west archipelago of Finland. J. Fish Biol. 34: 417-427. Rantajärvi, E. (ed.) 1998. Phytoplankton blooms in the Finnish sea areas and in the Baltic Proper during 1997. Meri - Report Series of the Finnish Institute of Marine Research 36: 5-8. Rantala, L. 1997a. Tornion tehtaiden velvoitetarkkailu v. 1996. I Kuormitus. PSV-Maa ja Vesi. 9 p. + app. Rantataro, J. 1992. pääkaupunkiseudun edustan vedenalaisen maa-ainesvarojen kartoitus. Helsingin seutukaavaliiton julkaisuja C31. 84 p. +app. Rask, M. 1989. A note on the diet of roach, Rutilus rutilus L., and other cyprinids at

Tvärminne, northern Baltic Sea. Aqua Fennica 19: 19-27. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 129 Rekolainen, S. 1989. Phosphorus and nitrogen load from forest and agricultural areas in Finland. Aqua Fennica 19: 95-107. Rekolainen, S., Pitkänen, H., Bleeker, A. & Felix, S. 1995. Nitrogen and phosphorus fluxes from Finnish agricultural areas to the Baltic Sea. Nordic Hydrology 26: 55-72. Roots, O. 1996. Toxic chlororganic compounds in the ecosystem of the Baltic Sea. Eesti Vabariigi Keskonnaministeerium. Tallinn. 1996. Ruuskanen, A. & Bäck, S. 1999. Does environmental stress affect fertility and frond regeneration of Fucus vesiculosus? Ann. Bot. Fennici 36: 285-290. Ryther, J.H. & Dunstan, W.M. 1971. Nitrogen, Phosphorus and eutrophication in the coastal marine environment. Science 171: 1008-1013. Räinä, P., Kauppinen, V., Kantola, L. & Viitanen, P. 1991. Kaskisten edustan merialueen velvoitetarkkailu 1990. Pohjois-Suomen vesitutkimustoimisto. 70 p. + app. Räisänen, R. 1997. Turun merialueen pohjaeläintutkimus vuonna 1995. Lounais-Suomen vesiensuojeluyhdistys ry. Tutkimusselosteita 119. 49 p. + app. Räisänen, R. & Jumppanen, K. 1996. Turun ympäristön merialueen tarkkailututkimus vuonna 1995. Vuosiyhteenveto. Lounais-Suomen vesiensuojeluyhdistys. Tutkimusselosteita 117. 66 p. + app. Räisänen, M., & Viljamaa, H. 1998. Kasviplanktonin lajisto ja biomassa sekä a-klorofylli. In: L. Pesonen (toim.). Helsingin ja Espoon merialueiden velvoitetarkkailu vuonna 1996. Helsingin kaupungin ympäristökeskuksen julkaisuja 4/98. Helsinki 1998, 101 p.+ 4 app.. Rönnberg & Mathiesen 1997. Long-term changes in the marine macroalgae of Lågskär, Åland sea (N Baltic). Nord. J. Bot. 18: 379-384. Rönnberg, O. 1991. Förändringar i bottenvegetationen i åländska skärgårdsvatten. Mem. Soc. Fauna Flora Fennica 67:102-106. Rönnberg, O., Lehto, J. & Haahtela, I. 1985. Recent changes in the occurrence of Fucus vesiculosus L. in the archipelago Sea SW Finland. Ann. Bot. Fennici 22:231-244. Salemaa, H. & Hietalahti, V. 1993. Hemimysis anomala G.O. Sars (Crustacea: Mysidacea) - Immigration of a Pontocaspian mysid into the Baltic Sea. Ann. Zool. Fennici 30: 271-276. Sanden, P., Pitkänen, H. & Eloheimo, K. 1996. Gulf of Bothnia, Hydrochemistry. In: HELCOM 1996. Third periodic assessment of the state of the marine environment of the Baltic Sea, 1989-1993; Background document. Baltic Sea Environ. Proc. 64B: 29-38. Saulamo, K. & Lehtonen, H. 1998. Vimman biologia ja vimpakantojen tila Suomen rannikoilla. Kala- ja riistaraportteja 130, 29 pp. (in Finnish). Sternbeck, J., Skei, J., Verta, M. & Östlund, P. 1999. Mobilisation of sedimentary trace metals following improved oxygen conditions - an assessment of the effects of a lower primary productivity on trace metal cycling in the Baltic Sea. TemaNord 1999;594. Copenhagen, Nordic Council of Ministers. Stigzelius, J., Kangas, P. & Andersin, A.-B. 1998. Long-term changes in soft bottom macrofauna in the Tvärminne area, Northern Baltic Sea. In prep. Stigzelius, J., Laine, A., Rissanen, J., Andersin, A.-B. & Ilus, E. 1997. The introduction of Marenzelleria viridis (Polychaeta, Spionidae) into the Gulf of Finland and the Gulf of Bothnia (northern Baltic Sea). Ann. Zool. Fennici 34:205-212. Sunila, I. 1981. Reproduction of Mytilus edulis L. (Bivalvia) in a brackish water area, the Gulf of Finland. Ann. Zool. Fennici 18:121-128. Swedish EPA. 1991. Metaller i Svenska Havsområden. Swedish Environmental Protection Agency, report 3696. (In Swedish). Södergren, A. 1989. Biological effects of bleached pulp mill effluents. Final report from the Environment/ Cellulose I Project., National Swedish Environmental Protection Board. REPORT 3558. Talsi, T. 1987. Porvoon edustan merialueen tila ja sen kehitys vuosina 1965-1984. Vesi- ja Ympäristöhallinnon julkaisuja no 5,172 p. Tamminen, T. 1990. Eutrophication and the Baltic Sea: Studies on phytoplankton, bacterio- plankton, and pelagic nutrient cycles. Academic disertation. Helsingfors. 22 p. Tamminen, T. & Kivi, K. (toim.) 1996. Typpikuormitus, ravinnekierrot ja rannikkovesien

rehevöityminen. PELAG III loppuraportti. 76 s. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

130 ○○○○○○○○○○○○○ The Finnish Environment 472 Tarrason, L. & Schaug, J. 1999. Transboundary Acid Deposition in Europe. EMEP Summary Report 1999. EMEP Report 1/99. Vahteri, P. 1997. Kemira Pigments Oy. Porin edustan merialueen pohjaeläintarkkailu v. 1995 ja 1996. Kokemäenjoen vesistön vesiensuojeluyhdistys. 21 p. + app. Valovirta,I. & Porkka, M. 1996. The distribution and abundance of Dreissena polymorpha (Pallas) in the eastern Gulf of Finland. Mem. Soc. Fauna Flora Fennica 72:63-78. Varmo, R. & Riiheläinen, T. Pohjaeläimistö ja pohjasedimentti Helsingin ja Espoon merialuilla vuonna 1991. Helsingin kaupungin ympäristökeskuksen julkaisuja 10/94. Vartiainen, T., Parmanne, R. & Hallikainen, A. 1997. Ympäristömyrkkyjen kertyminen silakkaan. Ympäristö ja Terveyslehti 7-8/97:18-22. Verta, M., Korhonen, M., Lehtoranta, J., Salo, S., Vartiainen, T., Kiviranta, H., Kukkonen, J., Hämäläinen, H., Mikkelson, P. & Palm, H. 1999a. Ecotoxicological and health effects caused by PCP’s, PCDE’s, PCDD’s and PCDF’s in river Kymijoki sediments, South- Eastern Finland. Organohalogen Compounds 43:239-242. Verta, M., Lehtoranta, J., Salo, S., Korhonen, M. & Kiviranta, H. 1999b. High concentrations of PCDD’s and PCDF’s in river Kymijoki sediments, South-Eastern Finland, caused by wood preservative Ky-5. Organohalogen Compounds 43: 261- 264. Verta, M., Ahtiainen, J., Hämäläinen, H., Jussila, H., Kiviranta, H., Korhonen, M., Kukkonen, J., Lehtoranta, J., Lyytikäinen, M., Malve, O., Mikkelson, P., Moisio, V., Niemi, A., Paasivirta, J., Palm, H., Rantalainen, A-L., Salo, S., Vartiainen, T. & Vuori, K-M. 1999c. Organoklooriyhdisteet ja raskasmetallit Kymijoen sedimentissä; esiintyminen, kulkeutuminen, vaikutukset ja terveysriskit. Suomen ympäristö 334. Villa, L. 1989. Sedimentin öljypitoisuus Porvoon edustan merialueella 1987. Helsingin vesi- ja ympäristöpiiri. Raportti. 5 p. Voipio, A. 1969. On the cycle and balance of phosphorus in the Baltic Sea. Suomen Kemistilehti 42: 48-54. Vuorinen, P., Paasivirta, J., Vuorinen, M., Peuranen, S. & Hoikka, J. 1993. Lohen ja meritaimenen ympäristömyrkkypitoisuudet ja lohen alkio- ja poikaskuolleisuus. Kalatutkimuksia 65: 71 p. Riista- ja kalatalouden tutkimuslaitos. Vuorinen, P.J., Paasivirta, J., Keinänen, M., Koistinen, J., Rantio, T., Hyötyläinen, T. & Welling, L. 1997. The M74 syndrome of Baltic salmon (Salmo salar) and organochlorine concentrations in the muscle of female salmon. Chemosphere 34, p. 1151-1166. Vuoristo, H. 1998. Water quality classification of Finnish inland waters. European Water Management Vol. 1, No. 6. Vuoristo, H. 1991. Pintavesien yleinen käyttökelpoisuus 1980-luvun alussa. National Board of Waters and the Environment Report No. 327, Helsinki. Välipakka, P., Antsulevich, A., Vaittinen, J. & Taskinen, J. 1997. The zebra mussel (Dreissena polymorpha) - a new important element in the fauna of Finland. - Abstracts of the BMB 15 and ECSA 27 Symposium, Mariehamn, Finland, 9-13 June 1997. p.76 Westerbom, M. 1999. Populationsstruktur och tillväxthastighet hos sex blåmusslepopulationer i norra Östersjön: ett spatiellt och temporalt perspektiv. Pro-gradu (69s.) Institutionen för ekologi och systematik, Helsingfors Universitet. Wiik, T. 1999. Merialueen kuha (Pikeperch in coastal waters). Official Statistics of Finland, SVT Agriculture, Forestry and Fishery 1999:4, p. 33-35. Wiik, T. & Kuikka, S. 1998. Merialueen kuha (Pikeperch in coastal waters). Official Statistics of Finland, SVT Environment 1998:13, p. 42-45. Ådjers, K., Böhling, P., Kangur, M. & Neuman, E. 1997. Monitoring in Baltic Coastal Reference Areas 1996. Composition of Fish Communities. Kala- ja riistaraportteja nro 90, 21 pp. Öst, M. & Kilpi, M. 1997. A recent change in size distribution of blue mussels (Mytilus edulis) in the western part of the Gulf of Finland. Ann. Zool. Fennici 34:31-36. Östlund, P., Sternbeck, J. & Brorström-Lundén, E. 1998. Metaller, PAH, PCB och

totalkolväten i sediment runt Stockholm- flöden och halter. IVL Rapport B 1297. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

The Finnish Environment 472 ○○○○○○○○○○○○○ 131 Documentation page Publisher Date Finnish Environment Institute March 2001 Author(s) Kauppila, Pirkko and Bäck, Saara (eds)

Title of publication The state of Finnish coastal waters in the 1990s

Parts of publication/ The publication is also available in the internet other project http://www.vyh.fi/palvelut/julkaisu/elektro/fe472/fe472.htm publications Abstract The Finnish coastal waters received annually on average 4 100 t of P and 74 000 t of N from its catchment during the 1990s. Agriculture was the main anthropogenic source of P and N loading.The load of P has decreased by 16% and the load of N 10% from the level of the late 1980s. The surface area of the eutrophied areas (3–5 Chl m-3) increased in the Gulf of Finland, the Archipelago Sea and the Bothnian Bay in the late 1980s. The situation has not essentially changed during the 1990s. In the Gulf of Finland, the increase in P concentrations levelled out in the late 1990s. Algal accumulations have intensified in the Gulf of Finland and the Archipelago Sea. This is partly explained by the decrease in N concentrations and partly by the increase in P concentrations due to the acceleration of internal loading. In the Gulf of Bothnian, N concentrations have usually slightly increased. Eutrophication is reflected in changes in the community structure and production of phytobenthos, zoobenthos and fish stocks. The growth depth of brown algae has diminished due to the increase in turbidity, and mass occurrences of filamentous algae have increased, leading to an increase in the production of organic matter. The state of bottom fauna has deteriorated in the Gulf of Finland and the Archipelago Sea due to weakened oxygen conditions in bottom layers. Regarding fish catches, eutrophication has been reflected in the increase of the dominance of roach. Some new alien species have become adapted in the1990s. Concentrations of harmful substances are usually below the levels measured in the other parts of the Baltic. Concentrations of heavy metals in sediment are highest in the Bothnian Bay and in the eastern Gulf of Finland. High concentrations of heavy metals and organic compounds in sediment and biota were recorded in areas affected by industrial waste waters. Keywords Baltic Sea, coastal waters, loading, eutrophication, harmful substances, environmental changes

Publication series and number The Finnish Environment 472

Theme of publication Environmental protection

Project name and number, if any

Financier/ commissioner Finnish Environment Institute

Project organization

ISSN ISBN 1238-7312 952-11-0878-9 No. of page Language 134 English Restrictions Price For public use 231 FIM For sale at/ distributor Edita Ltd, tel. +358 9 566 0266, fax +358 9 566 0380 Oy Edita Ab, Asiakaspalvelu, Pl 800, 00043 Edita, Finland e-mail: [email protected] www-server: http://www.edita.fi/netmarket

Financier of publication Finnish Environment Institute, P.O. Box 140, FIN-00251 Helsinki, Finland

Printing place and year Vammalan Kirjapaino Oy, 2001

132 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○The Finnish Environment 472 Kuvailulehti Julkaisija Julkaisuaika Suomen ympäristökeskus Maaliskuu 2001 Tekijä(t) Kauppila, Pirkko ja Bäck, Saara (toim.) Julkaisun nimi Suomen rannikkovesien tila 1990-luvulla

Julkaisun osat/ Julkaisu on saatavana myös internetistä muut saman projektin tuottamat julkaisut http://www.vyh.fi/palvelut/julkaisu/elektro/fe472/fe472.htm Tiivistelmä Suomen rannikkovedet vastaanottivat 1990-luvulla valuma-alueeltaan keskimäärin 4 100 tonnia fosforia ja 74 000 tonnia typpeä vuodessa. Maatalous oli suurin yksittäinen typen ja fosforin kuormituslähde. Fosforin kuormitus on pienentynyt 1980-luvun loppuun verrattuna reilut 16 % ja typen kuormitus noin 10 %. Rehevöityneiden alueiden (3–5 mg Chl m-3) pinta-ala kasvoi 1980- luvun lopulla Suomenlahdella, Saaristomerellä ja Perämerellä. Tilanne ei ole oleellisesti muuttunut 1990-luvulla. Eräiden voimakkaasti kuormitettujen alueiden rehevyys on vähentynyt kuormituksen pienentymisen seurauksena. Suomenlahdella fosforipitoisuuksien kasvu taittui vuosikymme- nen lopulla. Kasviplanktonkukinnot ovat voimistuneet Suomenlahdella ja Saaristomerellä. Tämä johtuu osittain typpipitoisuuksien vähentymisestä ja osittain fosforipitoisuuksien kasvusta sisäi- sen kuormituksen kiihtymisen seurauksena. Pohjanlahdella typpipitoisuudet ovat yleensä lievästi vähentyneet 1990-luvulla. Rehevöityminen näkyy makrolevien ja pohjaeläinten sekä kalakantojen yhdyskuntarakenteen muutoksina. Rakkolevien kasvusyvyys on pienentynyt sameutumisen vuoksi, ja makroleväyhdyskunnat muuttuneet rihmalevävaltaisiksi. Myös irtonaisina kasvavien rihmalevien massa-esiintymät ovat lisääntyneet, mikä on nostanut orgaanisen aineksen määrää. Pohjaneläinten tila on heikentynyt Suomenlahdella ja Saaristomerellä pohjan happiolojen heik- kenemisen seurauksena. Kalakannoissa rehevöityminen on ilmennyt mm. särkivaltaisuuden lisääntymisenä. Rannikkovesiimme vakiintui uusia tulokaslajeja 1990-luvulla. Haitallisten aineiden pitoisuudet jäivät yleensä Suomen rannikkovesissä Itämerestä mitattujen keskiarvojen ala- puolelle. Raskasmetallien pitoisuudet sedimentissä olivat korkeimmat Perämerellä ja Suomenlah- den itäosissa. Korkeita raskasmetallien ja orgaanisten yhdisteiden pitoisuuksia sedimentistä ja eliöstöstä tavattiin teollisuuden jätevesien vaikutuspiirissä.

Asiasanat Itämeri, rannikkovedet, kuormitus, rehevöityminen, haitalliset aineet, ympäristömuutokset

Julkaisusarjan nimi ja numero Suomen ympäristö 472 Julkaisun teema Ympäristönsuojelu Projektihankkeen nimi ja projektinumero Rahoittaja/ toimeksiantaja Suomen ympäristökeskus ISSN ISBN 1238-7312 952-11-0878-9 Sivuja Kieli 134 englanti Luottamuksellisuus Hinta julkinen 231 mk Julkaisun myynti/ jakaja Oy Edita Ab, Asiakaspalvelu, Pl 800, 00043 Edita puh. (09) 566 0266, telefax (09) 566 0380, sähköpostiosoite: [email protected] www-palvelin: http://www.edita.fi/netmarket Julkaisun kustantaja Suomen ympäristökeskus, PL 140, FIN-00251 Helsinki

Painopaikka ja -aika Vammalan Kirjapaino Oy, 2001

The Finnish Environment 472 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 133 Presentationsblad Utgivare Datum Finlands miljöcentral Mars 2001 Författare Kauppila, Pirkko och Bäck, Saara (red.)

Publikationens titel Tillståndet i Finlands kustvatten på 1990-talet

Publikationens delar/ andra publikationer Publikationen finns även i internet inom samma projekt http://www.vyh.fi/palvelut/julkaisu/elektro/fe472/fe472.htm

Sammandrag Finlands kustvatten mottog på 1990-talet från sina avrinningsområden i medeltal 4 100 ton fosfor och 74 000 ton kväve per år. Jordbruket var den största enskilda belastningskällan för kväve och fosfor. Fosforbelastningen har minskat jämfört med 1980-talet med över 16 % och kvävebelast- ningen med cirka 10 %. De eutrofierade områdenas (3–5 mg Chl m-3) yta ökade under 1980-talet i Finska viken, Skärgårdshavet och Bottenviken. Situationen har inte ändrats nämnvärt på 1990- talet. Vissa kraftigt belastade områdens eutrofigrad har minskat som en följd av att belastningen har minskat. I Finska viken stannade ökningen av fosforhalterna vid slutet av årtiondet. Växtp- lanktonblomningarna har blivit kraftigare i Finska viken och Skärgårdshavet. Detta beror till en del på minskningen av kvävehalterna och delvis på ökningen av fosforhalterna då den inre belastningen har trappats upp. I Bottenviken har kvävehalterna i allmänhet minskat något på 1990-talet. Eutrofieringen syns som en förändring av samhällsstrukturen hos makroalgerna, bottendjuren och fiskbestånden. Blåstångens växtdjup har minskat på grund av grumling, och bestånden av makroalger domineras nu av trådalger. Även massförekomsterna av fritt växande trådalger har ökat, vilket höjt mängden organiskt material. Bottendjurens tillstånd har försvagats i Finska viken och Skärgårdshavet som en följd av att syreförhållandena i botten har blivit sämre. I fiskbestånden ses eutrofieringen som en ökning av mörtfisk. Våra kustvatten fick nya bofasta invandrare på 1990- talet. Halterna skadliga ämnen stannade i allmänhet i de finska kustvattnen under medeltalet för hela Östersjön. Tungmetallhalterna i sedimenten var högst i Bottenviken och i Finska vikens östra delar. Höga halter tungmetaller och organiska föreningar i sediment och organismer påträffades inom verkningsområdena för inudstrins avloppsvatten

Nyckelord Östersjön, kuster, belastning, eutrofiering, skadliga ämnen, ändringar, miljö.

Publikationsserie och nummer Miljön i Finland 472

Publikationens tema Miljövård Projektets namn och nummer Finansiär/ uppdragsgivare Finlands miljöcentral Organisationer i projektgruppen ISSN ISBN 1238-7312 952-11-0878-9 Sidantal Språk 134 engelska Offentlighet Pris offentlig 231 mk Beställningar/ distribution Edita Ab, Kundservice, Pl 800, 00043 Edita puh. (09) 566 0266, telefax (09) 566 0380, e-mail: [email protected] www-server: http://www.edita.fi/netmarket

Förläggare Finlands miljöcentral, PB 140, FIN-00251 Helsingfors

Tryckeri/

tryckningsort och -år Vammalan Kirjapaino Oy, 2001 ○○○○○○○○○○○○

134 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ The Finnish Environment 472 472 The Finnish Environment The Finnish Environment 472 The stateofFinnishcoastalwatersinthe1990s

ENVIRONMENTAL ENVIRONMENTAL PROTECTION PROTECTION

The state of Finnish coastal waters in the 1990s Pirkko Kauppila and Saara Bäck (eds)

quality in Finnish coastal waters. The report is based on the results of different monitoring

programmes, loading statistics and studies concerning the state of Finnish coastal water areas. In

this report data and information have been collected using the national data bases in which the

monitoring data are stored and maintained. In addition to nutrients and harmful substances,

monitoring data of phytoplankton and macrozoobenthos are also evaluated. Moreover, the available

data on phytobenthos changes originated from separate research projects were evaluated. The

report covers the years from the the early 1980s to 1998/2000.

The report cover the following topics

• loading of nutrients and harmful substances originating from different sources

• assessment of the effects of loading on chemical and biological water quality in coastal areas

• assessment of changes in the state of coastal waters during the 1990s and reasons for those

• phytobenthos and macrozoobenthos changes as a measure of the state of coastal waters

• changes in fish populations and fisheries

ISBN 952-11-0878-9 ISSN 1238-7312